DWQ-2025-000592

Draft 2026 Integrated Report 303(d)
Assessment Methods

Prepared by Utah Department of Environmental Quality
Division of Water Quality
2
Table of Contents

Table of Contents ...................................................................................................................................................................................... 2
Abbreviations........................................................................................................................................................................................... 4
Figures ..................................................................................................................................................................................................... 7
Tables ...................................................................................................................................................................................................... 9
Assessment Methods Revisions Summary ............................................................................................................................................. 10
Chapter 1 303(d) Assessment Methods .................................................................................................................................................... 10
Introduction ................................................................................................................................................................................................. 11
The Clean Water Act and the Integrated Report ..................................................................................................................................... 11
Assessment Categories for Surface Waters ............................................................................................................................................. 11
Utah’s Numeric Criteria and Beneficial Uses ........................................................................................................................................... 13
Assessed Parameters............................................................................................................................................................................... 14
Assessment Process and Time Frames ........................................................................................................................................................... 15
Developing the Methods ......................................................................................................................................................................... 15
Public Review of the Methods Process and Schedule ............................................................................................................................. 15
Call for Readily Available Data and Schedule .......................................................................................................................................... 15
Developing the Components of the Draft Integrated Report and 303(d) List .......................................................................................... 18
Public Review of the 303(d) List .............................................................................................................................................................. 19
Finalizing the Integrated Report and 303(d) List ..................................................................................................................................... 20
Scope of the Assessment .............................................................................................................................................................................. 20
Waters of the State ................................................................................................................................................................................. 20
Waterbody Types .................................................................................................................................................................................... 21
Assessment Units .................................................................................................................................................................................... 21
Waters Within and Shared with Other States ......................................................................................................................................... 23
Data Quality ................................................................................................................................................................................................. 24
Credible Data Defined ............................................................................................................................................................................. 24
Components for Credible Data ................................................................................................................................................................ 24 Credible Data Matrices ............................................................................................................................................................................ 26
Data Submission Process ............................................................................................................................................................................... 30
Type of Data to Submit ........................................................................................................................................................................... 30
Period of Record ..................................................................................................................................................................................... 30
Data Submission Tools ............................................................................................................................................................................ 31
Data Preparation for Conventional and Toxic Assessments for All Waters ................................................................................................... 31
Results below Detection Limits ............................................................................................................................................................... 31
Duplicate and Replicate Results .............................................................................................................................................................. 31
Initial Assessment: Monitoring Location Site Level ................................................................................................................................. 32
Assessments Specific to Rivers, Streams, and Canals .................................................................................................................................... 32
Conventional Parameter Assessments .................................................................................................................................................... 32
Nutrient Assessments Specific to Headwater Streams ............................................................................................................................ 39
Narrative Standards: Biological Assessments .......................................................................................................................................... 44
Assessments Specific to Lakes, Reservoirs, and Ponds .................................................................................................................................. 47
Assessment Overview ............................................................................................................................................................................. 47
Tier I Assessment .................................................................................................................................................................................... 47
Tier II Assessment.................................................................................................................................................................................... 53
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Great Salt Lake ........................................................................................................................................................................................ 55
Toxic Parameter Assessments for All Waters ................................................................................................................................................. 56
Equation-Based Toxic Parameters ........................................................................................................................................................... 56 Assessment Process ................................................................................................................................................................................ 57
Data Preparation ..................................................................................................................................................................................... 58
Assessment Process ................................................................................................................................................................................ 59
Pollution Indicator Assessments for All Waters .............................................................................................................................................. 64
Narrative Standards for All Waters................................................................................................................................................................ 64
Fish Kills ................................................................................................................................................................................................... 65
Harmful Algal Blooms (HAB).................................................................................................................................................................... 65
Fish Tissue Assessments and Consumption Health Advisories ................................................................................................................ 66
Determinations of Impairment: All Assessment Units ................................................................................................................................... 67
Individual Assessment of Water Quality Standards ................................................................................................................................. 68 Conflicting Assessments of Water Quality Standards .............................................................................................................................. 68
Aggregation of Site-Specific Assessments to Assessment Unit Categories .............................................................................................. 68
Secondary Review ................................................................................................................................................................................... 69
Identifying Causes of Impairments ................................................................................................................................................................ 70
Pollutants ................................................................................................................................................................................................ 71
Unknown Sources ................................................................................................................................................................................... 71
Natural Conditions .................................................................................................................................................................................. 71
Revising the 303(d) List and Other Categorical Assessments ........................................................................................................................ 72
Category 4A ............................................................................................................................................................................................. 72
Category 4B ............................................................................................................................................................................................. 73
Category 4C ............................................................................................................................................................................................. 73
Delistings ................................................................................................................................................................................................. 74
Previous Categorical Listings ................................................................................................................................................................... 77
303(d) Vision and TMDL Priority Development .............................................................................................................................................. 78
Revision Requests between Cycles ................................................................................................................................................................. 78
Literature Cited ............................................................................................................................................................................................ 79
Appendix 1 .............................................................................................................................................................................................. 81
Data Quality Guideline Examples .................................................................................................................................................................. 81
DWQ Sampling Analysis Plan Requirements ........................................................................................................................................... 81 Appendix 2 .............................................................................................................................................................................................. 84
Application of Secondary Review Process ....................................................................................................................................................... 84
Appendix 3 .............................................................................................................................................................................................. 87
Summarizing Assessments From Site to Assessment Unit Level ................................................................................................................... 87
Appendix 4 .............................................................................................................................................................................................. 91
4B Submission Policies and Procedures: Process for Determining Category 4B Classification ...................................................................... 91
Appendix 5 .............................................................................................................................................................................................. 93
Delisting Guidelines ...................................................................................................................................................................................... 93

4
Abbreviations

Abbreviation Definition
< less than
> greater than
≤ less than or equal to
≥ greater than or equal to
AGRC Automated Geographic Reference Center
ATTAINS The Assessment, Total Maximum Daily Load, Tracking and
Implementation System. This EPA- maintained database is an
online system for accessing information about the conditions of the
Nation’s surface waters.
AU assessment unit
Ca calcium
CFR Code of Federal Regulations
Chl-a chlorophyll a
CWA Clean Water Act
DEQ Utah Department of Environmental Quality
DO dissolved oxygen
DWQ Utah Division of Water Quality
E expected
E. coli Escherichia coli
EPA U.S. Environmental Protection Agency
ER ecosystem respiration
g grams
GIS geographic information systems
GPP gross primary productivity
GSL Great Salt Lake
5
GRAMA Government Records Access and Management Act
HAB(s) harmful algal bloom(s)
HH human health
HUC hydrologic unit
IR Integrated Report
kg kilogram
L liter
Mg magnesium
mg milligram
mg/kg milligram per kilogram
mg/L milligram per liter
mL milliliter
MLID monitoring location identifier
MPN most probable number
NHD National Hydrologic Dataset
O observed
O/E observed/expected
Pc probability of capturing
ppm parts per million
QA quality assurance
QA/QC quality assurance/quality control
QC quality control
QAPP quality assurance project plan
RIVPACS River Invertebrate Prediction and Classification System
SAP(s) sample analysis plan(s)
SD standard deviation
SDD Secchi disk depth
SOP(s) standard operating procedure(s)
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T temperature
TDS total dissolved solids
TMDL total maximum daily load
TN total nitrogen
TP total phosphorus
TSI trophic state index
UAC Utah Administrative Code
UDOH Utah Department of Health
USGS U.S. Geological Survey
WMU watershed management unit
WQP (EPA’s) Water Quality Portal
WQS water quality standard
μg/L microgram per liter

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Figures

Figure 1. Utah Division of Water Quality assessment unit delineations. ........................................................................................................ 23
Figure 2. Overview of the assessment process for conventional parameters using grab sample data. ......................................................... 34
Figure 3. Overview of the assessment process for the minimum dissolved oxygen, daily minimum, using high frequency data. ................ 36
Figure 4. Overview of the assessment process for the minimum dissolved oxygen, 7-day averages using high frequency data. ................. 37
Figure 5. Overview of the assessment process for the minimum dissolved oxygen, 30-day averages, using high frequency data. .............. 38
Figure 6. Overview of the assessment process to determine support of recreational life uses based on nutrient enrichment in headwater
streams. ........................................................................................................................................................................................................... 43
Figure 7. A hypothetical example of O/E as a standardization of biological assessments. ............................................................................. 44
Figure 8. Decision tree for making biological assessment decisions. .............................................................................................................. 45
Figure 9. Process using conventional (nontoxic) parameters to assess lakes that are mixed. ........................................................................ 48
Figure 10. Plots of pH measurements (blue dots) against lake depth for a waterbody meeting (Panel A) and exceed (Panel B) the pH water
quality standards. ............................................................................................................................................................................................ 49
Figure 11. Plots of temperature measurements (blue dots) against lake depth for two sites to provide an example of assessment
procedures. Note: The red line illustrates a temperature criterion of 20 degrees Celsius: Class 3A beneficial use. ...................................... 50
Figure 12. Beneficial use support based on the existence of adequate habitat. ............................................................................................ 51
Figure 13. Concept of the habitable zone where both DO and temperature are suitable for aquatic life. The site depicted on the top
(Panel A) would be considered supporting because the lens where both temperature and DO provide sufficient habitat is greater than
three continuous meters (>=3 m). Conversely, the site on the bottom (Panel B) is not supporting aquatic life uses because although there
are regions in the water column where dissolved oxygen and temperature criteria are met separately, the region of overlap in the water
column for both temperature and dissolved oxygen criteria (approximately 8 meters depth) is less than three meters. ............................ 52
Figure 14. Assessment process to determine support of the agricultural beneficial use with TDS data. ....................................................... 53
Figure 15. Tier II assessment process for lakes, reservoirs, and ponds. .......................................................................................................... 54
Figure 16. Overview of the assessment process for toxic parameters. .......................................................................................................... 57
Figure 17. Considering E. coli-related beach closures and/or health advisories. ............................................................................................ 59
Figure 18. Scenario A: A seasonal assessment using the maximum criterion at a monitoring location. ........................................................ 61
Figure 19. Scenario B: An assessment using the 30-day geometric mean for monitoring locations with five or more collection events
within 30 days. ................................................................................................................................................................................................ 62
Figure 20. Scenario C: A seasonal geometric mean assessment. .................................................................................................................... 63
Figure 21. Process of assigning EPA categories to AUs based on results of monitoring location assessments. ............................................. 69
Figure 22 Assessment Unit Decision: Category 5 (Not supporting) for beneficial use 2 based on pH assessment and Category 4A for
beneficial use 1 based on temperature assessment. Temperature is associated with an existing TMDL. ..................................................... 88
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Figure 23 Assessment Unit Decision: Category 4A (Approved TMDL) for beneficial use 1 based on temperature assessment. ................... 88
Figure 24 Assessment Unit Decision: Category 3 (Insufficient Data) based on both beneficial uses and parameter assessments at all four
sites. ................................................................................................................................................................................................................ 89
Figure 25 Assessment Unit Decision: Category 2 (No Evidence of Impairment) due to full support of beneficial use 1 based on the pH
assessments and insufficient data to assess beneficial use 2 across all sites. ................................................................................................ 89
Figure 26 Assessment Unit Decision: Category 1 (Fully Supporting) for beneficial uses 1 and 2 based on fully supporting pH and
temperature assessments at sites within the assessment unit. ..................................................................................................................... 90
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Tables
Table 1. U.S. Environmental Protection Agency categorization of assessed surface waterbodies for Integrated Report purposes. ............. 12
Table 2. Subclassifications of Utah's beneficial uses. ...................................................................................................................................... 13
Table 3. DWQ's data-availability matrix. ......................................................................................................................................................... 17
Table 4. Assessed waterbody types used for categorizing monitoring locations. ........................................................................................... 21
Table 5. Data validation criteria for water quality field grab sample parameters. ......................................................................................... 27
Table 6. Data validation criteria for water quality high frequency dissolved oxygen data. ............................................................................ 27
Table 7. Data validation criteria for water quality chemistry grab sample parameters. ................................................................................ 28
Table 8. Data validation criteria for macroinvertebrate data. ........................................................................................................................ 29
Table 9. Data validation criteria for Escherichia coli (E. coli) data. ................................................................................................................. 29
Table 10. Summary of data types considered by Utah’s IR program. ............................................................................................................. 30
Table 11. Conventional parameters and associated designated uses as identified for assessment purposes. .............................................. 32
Table 12. Numeric Nutrient Criteria and Associated Ecological Responses (Bioconfirmation Criteria) to Protect Aquatic Life Uses in
Antidegradation Category 1 and 2 (UAC R317-2-12) Headwater Perennial Streams. .................................................................................... 41
Table 13. Decision Matrix That Will Be Used to Assess Support of Headwater Aquatic Life Uses for Nutrient-related Water Quality
Problems ......................................................................................................................................................................................................... 42
Table 14. Beneficial use support determination for O/E values obtained from different sample sizes. ........................................................ 46
Table 15. Selenium trigger levels and DWQ responses (UAC R317-2-14.2(14)).............................................................................................. 55
Table 16. Cyanotoxin thresholds for recreational use assessments based on EPA (2019) guidance. ............................................................. 65
Table 17. Application of secondary review process ........................................................................................................................................ 84
Table 18. Description of EPA Delisting Codes .................................................................................................................................................. 94
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Assessment Methods Revisions Summary
Revisions Reasoning Location
Update the "5-Alt" description to "5R" and ensure the description links to the 2.0 Vision Prioritization. 2024 EPA Memo recommends referring to "5-Alt" as "5R". Table 1 Category Descriptions (pg. 13)
Revise language regarding the request for readily available data (IR Call for Data): “DWQ
issues a request for all readily available data after the Integrated Report (IR) Methods have
been finalized.”
Previous methods specified that the Call for
Data is published after November 1 of even-numbered years, which may not always align
with the Methods Public Comment period.
Assessment Process and
Time Frames: Call for Readily Available Data
Section (pg. 16)
Remove the phrase "no later than February 1." Update to: DWQ will release the proposed IR and 303(d)
list for a 30-day public comment period after July 1 of odd-numbered years and no later than
February 1 of even-numbered years.
IR timelines are subject to change, and the February 1 deadline may not always be applicable.
Assessment Process and Time Frames: Bullet (c) of Public Review of the 303(d) List (pg. 20)
Updates to Calibration of Temperature and pH Accuracy Table 5.
Table 5. Data Validation criteria for water quality field grab sample parameters were
updated to align with the validation criteria used by DWQ.
Table 5. Data Validation criteria for water quality
field grab sample parameters (pg. 29)
Add language to Table 11 (Temperature Assessments) specifying the use of high-frequency (HF) temperature data during secondary reviews.
DWQ is developing an assessment method for High Frequency Temperature data. For this cycle, DWQ is incorporating high frequency temperature data as part of the secondary review process.
Conventional Assessments Parameters Table 11 (pg. 36)
Specify that the harmful algal bloom (HAB) recreational season is defined as May 1
through October 31.
Previous methods only mentioned the recreational season in the E. coli assessment
methods. This revision ensures consistency by defining the recreational season in the harmful
algal bloom section.
Narrative Standards
Section: Harmful Algal Blooms (HAB) Subsection
(pg.70)
Update the 303(d) Vision and TMDL Development section including Utah's Prioritization 2.0, a strategic ten-year roadmap for water quality restoration and protection planning.
This addition reflects EPA's 2023 Vision 2.0 guidance for the 303(d) program and includes Utah's Prioritization 2.0 to address impaired waterbodies.
303(d) Vision and TMDL Priority Development Section (pg. 83)
Add guidance for the secondary review table to
include the use of HF temperature data in comparison with grab sample data.
Clarifies the process for reconciling HF and
grab sample temperature data during secondary reviews.
Application of Secondary
Review Process Table (pg. 91)
The changes listed in the summary table and other minor changes to the methods have been highlighted in yellow for ease of review.
Chapter 1 303(d) Assessment
Methods
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Introduction
The Clean Water Act and the Integrated Report
The rules and regulations of the federal Clean Water Act (CWA) require the Utah Division of Water Quality
(DWQ) to report the condition or health of all Utah surface waters to the U.S. Congress every other year. The
Integrated Report (IR) contains two key reporting elements defined by the CWA:
Statewide reporting under CWA Section 305(b): Section 305(b) reporting summarizes the overall
condition of Utah’s surface waters as well as key water quality concerns. These concerns can include
pollutants, habitat alteration, and sources of water quality problems.
Water quality assessments under CWA Section 303(d): Section 303(d) requires states to identify
waters that are not supporting beneficial uses according to state water quality standards (Utah Administrative
Code [UAC] R317-2-7.1). Utah’s Section 303(d) list (hereafter the 303(d) list) also prioritizes the total
maximum daily loads (TMDL) required for each listed waterbody and the cause of nonattainment. This list
includes waters impaired as a result of nonpoint sources, point source discharges, natural sources, or a
combination of sources.
In addition to Utah’s 303(d) list, DWQ also identifies
• Waterbodies meeting water quality standards
• Waterbodies with water quality problems that DWQ cannot confirm due to insufficient sample size,
uncertainty regarding the nature of the data or other factors
• Waterbodies either currently addressed by DWQ through a TMDL or other pollution-control mechanism
Full descriptions of these and other U.S. Environmental Protection Agency (EPA)-identified waterbody
assessment classifications are described and summarized in Table 1 .
Assessment Categories for Surface Waters
DWQ uses five categories defined by EPA to assess surface waters of the state (EPA, 2005). These
categories are described in Table 1.
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Table 1. U.S. Environmental Protection Agency categorization of assessed surface waterbodies for Integrated Report purposes. EPA Assessment Category Assessment Category Description
1 Supporting. All beneficial uses assigned to a waterbody are evaluated against one or more numeric criteria and each use is found to meet applicable water quality standards.
2 No Evidence of Impairment. Some, but not all, beneficial uses assigned to a waterbody are evaluated against one or more numeric criteria, and each assessed use is found to meet applicable water quality standards.
3
Insufficient Data and/or Information. There are insufficient data and information to conclude support or nonsupport of a use. The category may be applied when: (1) the dataset is smaller in size and has water quality criteria exceedances OR no water quality criteria exceedances; (2) a secondary review applied to a waterbody found it was not meeting water quality standards; (3) water quality criteria and/or beneficial use support assessment methods are not yet developed (or are undergoing development or revisions) so use
attainment has not been determined; (4) waterbodies were assessed against water quality parameters and characteristics that require further investigations as defined in UAC R317-2; (5) assessment units (AUs) have improper use designations, lack use designations,
or contain other inconsistencies in the dataset. In cases where no recent data are available, historic-listing determinations will be maintained.
4A TMDL-Approved. Waterbodies impaired by a pollutant with a TMDL(s) developed and approved by EPA. Where more than one pollutant is associated with the impairment, the waterbody and the parameters that have an approved TMDL are listed in this category. If a waterbody has other pollutants that need a TMDL, the waterbody is listed in Category 5 with an Approved TMDL.

4B
Pollution Control. Waterbodies that are not supporting designated uses where other pollution-control requirements, such as best management practices required by local, state, or federal authority, are stringent enough to bring the waters listed in this category back into attainment in the near future with the approved pollution-control requirements in place, consistent with 40 Code of Federal Regulations (CFR) 130.7(b) (I) (ii) and (iii). All waterbodies placed in this category must have a pollution control requirement plan developed and approved by EPA. Similar to Category 4A, if the waterbody has other pollutants that need a TMDL, or there is already a TMDL in place for another pollutant, the waterbody may also be listed in Categories 5 and 4A. Therefore, an AU with a pollution control
in place may be listed in Categories 4B, 4A, and 5.
4C
Non-Pollutant Impairment. Waterbodies not supporting designated uses are placed in this category if the impairment is not caused by a pollutant but rather by pollution (for example, hydrologic modification or habitat degradation). Similar to Categories 4A and 4B, if
the waterbody has other pollutants that need a TMDL, or there is an approved TMDL or pollution-control mechanism in place, the waterbody may also be listed in Categories 4A, 4B, and 5. Therefore, an AU with a non-pollutant impairment may be listed in Categories 4C, 4B, 4A, and 5.
5
Not Supporting. The concentration of a pollutant or several pollutants exceeds numeric water quality criteria, or beneficial uses are not-supporting based on violation of the narrative water quality standards. Waterbodies identified as “threatened” may also be placed
in this category. In a “threatened” waterbody, one or more of its uses are likely to become impaired by the next IR cycle and water quality may be exhibiting a deteriorating trend if pollution control actions are not taken. Both impaired and threatened waterbodies constitute Utah’s formal Section 303(d) list and are prioritized for future TMDL development.
5R Advance Restoration Plans . EPA’s 303(d) program vision promotes the identification of alternative approaches to TMDL development for impaired waters where these approaches would result in a more rapid attainment of water quality standards.
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Utah’s Numeric Criteria and Beneficial Uses
DWQ assesses the impacts of measured pollutant concentrations on designated beneficial uses to
determine the appropriate assessment categories for a waterbody (see Table 1). Utah has developed and
adopted water quality numeric criteria (chemical concentrations that should not be exceeded) to protect the
water quality of surface waters and the uses these waterbodies support (UAC R317-2-14). As noted in UAC
R317-2-14, the water quality criteria for a pollutant can vary depending on the beneficial use assigned to a
waterbody.
Utah adopted beneficial use classifications that identify the use and value of a waterbody for source water for
domestic water systems, recreation, aquatic wildlife, agriculture, and Great Salt Lake (see UAC R317-2-6).
DWQ currently designates five beneficial use classes of surface waters within the state:
• Class 1. Protected for use as a raw water source for domestic water systems
• Class 2. Protected for recreational use and aesthetics
• Class 3. Protected for use by aquatic wildlife
• Class 4. Protected for agricultural uses including irrigation of crops and stock watering
• Class 5. The Great Salt Lake (GSL)
Subclassifications for several of these categories are further defined in Table 2. Table 2. Subclassifications of Utah's beneficial uses.
Beneficial Use Subclassification Use Definition
1C Protected for domestic purposes with prior treatment by treatment processes as required by the Utah Division of Drinking Water
2A Protected for frequent primary contact recreation where there is a high likelihood of ingestion of water or a high degree of bodily contact with the water. Examples include, but are not limited to, swimming, rafting, kayaking, diving, and water skiing.
2B
Protected for infrequent primary contact recreation. Also protected for secondary contact recreation where there is a low likelihood of ingestion of water or a low degree of bodily contact with the water. Examples include, but are not limited to, wading, hunting, and fishing.
3A Protected for cold water species of game fish and other cold water aquatic life, including
the necessary aquatic organisms in their food chain.
3B Protected for warm water species of game fish and other warm water aquatic life, including the necessary aquatic organisms in their food chain.
3C Protected for nongame fish and other aquatic life, including the necessary aquatic organisms in their food chain.
3D Protected for waterfowl, shore birds and other water-oriented wildlife not included in Classes 3A, 3B, or 3C, including the necessary aquatic organisms in their food chain.
3E Severely habitat-limited waters. Narrative standards will be applied to protect these waters for aquatic wildlife. 4 Protected for agricultural uses including irrigation of crops and stock watering.

5A
Gilbert Bay
Geographical Boundary: All open waters at or below approximately 4,208-foot elevation south of the Union Pacific Causeway, excluding all of the Farmington Bay south of the Antelope Island Causeway and salt evaporation ponds. Beneficial Uses: Protected for frequent primary and secondary contact recreation, waterfowl, shore birds and other water-oriented wildlife including their necessary food chain.
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Beneficial Use Subclassification Use Definition

5B
Gunnison Bay
Geographical Boundary: All open waters at or below approximately 4,208-foot elevation north of the Union Pacific Causeway and west of the Promontory Mountains, excluding
salt evaporation ponds. Beneficial Uses: Protected for infrequent primary and secondary contact recreation, waterfowl, shore birds and other water-oriented wildlife including their necessary food chain.

5C
Bear River Bay Geographical Boundary: All open waters at or below approximately 4,208-foot elevation north of the Union Pacific Causeway and east of the Promontory Mountains, excluding salt evaporation ponds. Beneficial Uses: Protected for infrequent primary and secondary contact recreation, waterfowl, shore birds and other water-oriented wildlife including their necessary food chain

5D
Farmington Bay
Geographical Boundary: All open waters at or below approximately 4,208-foot elevation east of Antelope Island and south of the Antelope Island Causeway, excluding salt
evaporation ponds. Beneficial Uses: Protected for infrequent primary and secondary contact recreation, waterfowl, shore birds and other water-oriented wildlife including their necessary food chain.

5E
Transitional Waters along the Shoreline of the Great Salt Lake Geographical Boundary: All waters below approximately 4,208-foot elevation to the
current lake elevation of the open water of the Great Salt Lake receiving their source water from naturally occurring springs and streams, impounded wetlands, or facilities
requiring a UPDES permit. The geographical areas of these transitional waters change corresponding to the fluctuation of open water elevation. Beneficial Uses: Protected for
infrequent primary and secondary contact recreation, waterfowl, shore birds and other water-oriented wildlife including their necessary food chain.

Every beneficial use with numeric criteria and credible and readily available data is assessed and reported for
303(d) assessment purposes. DWQ assesses for all use class criteria for each waterbody where parameter
data are available. Where waterbodies are unclassified and do not have assigned beneficial uses in DWQ
data records, DWQ may assign default beneficial uses as articulated in UAC R317-2-13. Alternately, these
undefined waterbodies may be classified as an EPA Assessment Category 3 or not reported in the IR if an
Assessment Unit has not been established.
For more information on how DWQ develops, adopts, and updates the numeric criteria and beneficial uses in
UAC R317-2, please refer to DWQ’s Standards website.
Assessed Parameters
Water quality assessments may not report on all parameters listed in UAC R317-2-14. Assessments reflect parameters with adopted numeric criteria that also have readily available and credible datasets from the period of record. Monitoring and data availability for pollutants listed in UAC R317-2-14 may be constrained by:
• Laboratory resources that limit the ability to assess all parameters in UAC R317-2-14
• Significant monitoring and/or analytical costs associated with processing a sample or measuring a pollutant
• Logistical constraints due to monitoring location and holding times for certain parameters
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Assessment Process and Time Frames Developing the Methods
This document describes the most up-to-date assessment methods that will be applied to Utah’s current IR
cycle. Although most of the methods described have been applied in past assessment cycles, other methods
are new or modified from previous reporting cycles. Some of the assessment method revisions are intended
to clarify ongoing DWQ practices. Other more substantive revisions may be based on comments that were
raised during the previous IR’s 303(d) assessment methods and draft IR public comment periods.
DWQ updates and revises the 303(d) methods when concerns are raised or when program developments are
released by DWQ. Additional modifications or clarifications to the assessment methods may also be made
based on feedback provided by EPA during and after a reporting cycle; or from the EPA’s cycle-specific 303(d)
guidance memorandum.
All changes made to the 303(d) assessment methods are typically reviewed and updated on even-numbered
years in anticipation of developing the Draft IR and 303(d) list in the following odd-numbered year. This
process allows DWQ to consider comments and suggestions on assessment methods before a formal
analysis is conducted. This reduces the need to rework analyses from changes in methods.
Public Review of the Methods Process and Schedule
The development and acceptance of the Assessment Methods includes a public review process and occurs
on the following schedule:
a. DWQ releases the proposed Assessment Methods for a 30-day public comment period. The notice for public comments on the Assessment Methods are advertised on DWQ’s Public Notices webpage, and Utah’s Integrated Report program webpages. b. DWQ compiles and responds to the comments received within the 30-day public comment period. DWQ’s responses to comments are posted on the Utah’s Integrated Report program webpages. c. If substantive revisions to the Assessment Methods are adopted by DWQ based on comments
received in the public comment period, DWQ may hold a second public comment period of 30 days or less. Should DWQ proceed with a second public comment period, notifications will be advertised, at a minimum, on DWQ’s Public Notices webpages, and the Utah’s Integrated Report program webpages. d. Following the conclusion of the public comment period(s), DWQ posts responses to comments on the Utah’s Integrated Report program webpages. Any changes or additions that were made in
response to public comments will be documented and issued with the draft IR and 303(d) list. During the draft IR public comment period, comments on the Assessment Methods are
considered out of scope.
Concerns and comments received outside the public comment period will be considered in the next
assessment methods public review cycle.
Call for Readily Available Data and Schedule
DWQ issues a request for all readily available data (i.e., the IR Call for Data) after the IR Assessment
Methods have been finalized.
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Existing and Readily Available Data Defined
DWQ assembles and evaluates all existing and readily available data to determine whether a waterbody is
supporting or not supporting the assigned beneficial uses and numeric criteria in UAC R317-2 as mandated in
40 CFR 130.7(b)(5). For the purposes of the IR, existing and readily available data may include:
• Data and information referenced in 40 CFR 130.7(b)(5)(i),(iii), and (iv)
• Data collected by DWQ or DWQ cooperators for assessment purposes
• Data collected for other DWQ programs, such as waste load allocations, TMDL development, watershed planning, and use attainability analyses
• Data collected for narrative assessments (see Narrative Assessment: Biological Assessments and
Narrative Standards for All Waters)
• Data obtained through EPA’s Water Quality Portal (WQP)
• Data and information obtained through the IR’s public Call for Data
• Data and information submitted to EPA’s Water Quality Exchange System or DWQ’s Call for Data to
support a credible data submission (e.g., Table 5-8)
• Data included in the Data Types Matrix in Table 10
Data and information (as described above) that are not submitted during the IR’s Call for Data or
presented to DWQ in accordance with the schedule as outlined in this document and on Utah’s Integrated
Report program webpages will not be treated as readily available for the purpose of assessment decisions
during the current assessment cycle.
Data that are submitted to DWQ or obtained by DWQ during the IR data compilation process are integrated
into DWQ’s assessments as described in Table 3 and subject to DWQ’s data management and quality
assurance/quality control (QA/QC) processes. Should any data and information not be included in the
assessment process, DWQ will clearly document which dataset (or datasets) were not included and why as
described and required in 40 CFR 130.7(b)(6)(iii). Rejected datasets, along with detailed tables
summarizing the results of assessed parameters, their associated uses, and the resulting assessment
categories, will be published in DWQ’s final Integrated Report.
17
Table 3. DWQ's data-availability matrix. Data Availability Description Processing required Uses for Assessments

Readily available
Data are incorporated into EPA’s WQP database and can interface directly with DWQ’s IR data processing and assessment tools. Data is submitted by stakeholders or data submitters
through DWQ’s data submission templates or electronic submission processes which are provided on the Call for
Data webpage.1,2

None

Fully incorporate into DWQ’s assessment tools
Additional “other” sources of data included in the Data Types Matrix in Table 10 that described the waterbodies in 40 CFR 130.7(b)(5)(i), (iii), and (iv) and are submitted through DWQ’s electronic submission process as described on the Call for Data webpage.
None
Fully incorporate into DWQ’s Conflicting Assessments of Water Quality Standards and Secondary Review processes

Readily
available (additional processing may be required by DWQ)

Quantitative data and information may be stored in and routinely uploaded to a queryable, regularly maintained database that is available on the web or electronically submitted to DWQ during the public call for data. Database format is consistent and allows repeatable queries with predictable results (e.g., parameter names, location descriptions, and parameter units are consistent), making development of automated interface tools practicable.

Full incorporation into IR assessment tools requires DWQ development of interface tools for aggregating, translating, and harmonizing data to appropriate formats. In particular, sampling locations and dates, parameter names, fractions, units, analysis methods, and detection limits require translation and interpretation prior to assessment.
Fully incorporate into IR assessment tools if interface tools have been developed.2
If interface tools are still in the development phase, (1) screen data for exceedances for the waterbodies
described in 40 CFR 130.7(b)(5)(i), (iii), and (iv), or (2) manually assess
data for specific sites, dates, and parameters at the request of stakeholders or data submitters for waterbodies described in 40 CFR
130.7(b)(5)(i), (iii), and (iv). Results are fully incorporated into DWQ’s
Conflicting Assessments of Water Quality Standards and Secondary Review.
1 DWQ data submission templates and processes are designed to allow for data and information that may not fit the data structure of EPA’s Water Quality Exchange System. They may also be used to support a credible data review (Tables 5-8) or perform narrative or high frequency data assessments.
2 DWQ requests data submitters inform the Division which data system contains their data so DWQ can work with submitters prior to the IR’s Call for Data to develop interface tools.
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Developing the Components of the Draft Integrated Report and 303(d) List
DWQ reviews all data and assigns a credible data “grade” following its response to public comments on the
draft 303(d) Assessment Methods and compilation of all existing and readily available data. All non-rejected,
credible data are then used in the assessments. The final 303(d) Assessment Methods, 305(b) Summary, and
303(d) List of Impaired Waters are the minimum reporting elements included in the Integrated Report. These
reporting elements are available for public review and comment.
Final 303(d) Assessment Methods
The final version of the publicly-vetted 303(d) Assessment Methods, including any changes or additions made
in response to the Assessment Method public comment period(s) is posted on the Utah’s Integrated Report
program webpages.
305(b) Summary
This summary, at a minimum, will address the following elements for previous and new or updated
assessments:
• A unique identifier assigned to the Assessment Unit
• The name of the Assessment Unit
• The size and the unit of measure for the assessed waterbody type
• The EPA-defined assessment category for each defined and evaluated Assessment Unit
303(d) Assessment Results
At a minimum, the following information will be provided for previous and new or updated assessments:
• The minimum elements discussed above in the 305(b) Summary
• The name of the parameter assessed, the beneficial use associated with the assessed parameter, and
the EPA-defined assessment category status for the parameter and beneficial use
• The IR cycle the Assessment Unit was first listed for a cause
• The reason(s) for identifying the delisting of a waterbody
305(b) Summary and 303(d) Assessment Metadata
DWQ will provide (at a minimum) the following supporting information and documentation as referenced in
CFR 130.7 (b)(6) to support its decision to list or not list waters:
• A description of, and access to, the data records and information used in the IR’s current period of record
• A rationale for, and access to, any data and information that was obtained or submitted to DWQ during
the call for data but did not meet DWQ’s readily available or credible data requirements and was not used
for 305(b) and 303(d) assessments
• A rationale for, and access to, any rejected data records and information
For archiving purposes and to assist with the review of the IR and 303(d) List, DWQ will also provide the
following as time and resources allow:
• The assessment method type and the assessment method context as defined in ATTAINS
• Geolocation information on the waterbodies assessed
• The date and version of UAC R317-2 used in the assessment cycle
19
• The list of approved TMDLs used in the assessment cycle
• An executive summary of the Final IR results
Metadata Reported in ATTAINS
Along with the above information, DWQ will also report the following details in ATTAINS to ensure
comprehensive documentation of Assessment Units and their histories:
• An indicator of whether the Assessment Unit is currently active, or if the Assessment Unit identifier was
retired and being kept for historical tracking purposes and is part of an Assessment Unit history of
another Assessment Unit
• The waterbody type for the Assessment Unit
• The location description of the Assessment Unit
• The cycle the Assessment Unit was last assessed, which can include any conclusions related to this
Assessment Unit and delisting decisions (if appropriate)
• The beneficial use(s) designated to the Assessment Unit and the EPA-defined assessment categories
associated with the beneficial use after assessment
• A flag indicating whether or not the cause of the attainment status is a pollutant
Public Review of the 303(d) List
There will be a formal public review process for the IR and 303(d) list using the following steps:
• Any person who has a pollution-control mechanism plan for a waterbody and would like to submit that plan for consideration as a Category 4B, must first submit that plan to DWQ and then EPA for review and final approval. Once approved, the waterbody will be placed in Category 4B as part of the current IR cycle. Pollution Control Plans that are approved by DWQ and EPA after the IR is finalized will be considered in future IRs.
• Waters and pollutants that are considered for a potential Category 4A (approved TMDLs) must be
approved by DWQ’s Water Quality Board per UAC R317-1-7 and by EPA per 40 CFR 130.7. TMDLs that are approved by DWQ and EPA after the IR is finalized will be considered in future IRs.
• DWQ will release the proposed IR and 303(d) list for a 30-day public comment period. At a minimum, the notice for public comments on the IR will be advertised on the Public Notices and Utah’s Integrated Report program webpages.
• Stakeholders who wish to submit data for listing or delisting considerations are encouraged to submit that data and information during the Utah’s IR program’s Call for Data. However, DWQ may consider data that are submitted during the public comment period of the draft IR and 303(d) list when the commenter can show that submitted data could result in a change to a specific waterbody assessment decision. Data that are submitted during the public comment period for the draft IR must be submitted in the format articulated in this document and on the IR Call for Data website and be of Grade A or B quality to be used in an assessment decision (see Tables 5- 9). Information submitted during the public comment period will undergo a secondary review (see Secondary Review and Appendix 2).
• DWQ will compile and respond to comments that were received within the 30-day public
comment period after the close of the public comment period.
• DWQ may offer a second public comment period of 30 days or fewer if substantial revisions to the IR and 303(d) list are adopted on the basis of comments received during the first public comment period. Should DWQ proceed with a second public comment period, notifications will be advertised, at a minimum, on the Public Notices and the Utah’s Integrated Report program webpages.
• DWQ will submit a response to the public comments that were received during the 30-day public comment period and a final version of the IR and 303(d) list to EPA for final approval no later than April 1 of even-numbered years. DWQ will post a status update on the Utah’s Integrated Report
20
• program’s webpages to let stakeholders know that a final IR was submitted to EPA for final approval.
Any concerns or rebuttals from stakeholders regarding the IR will not be considered for the recently submitted IR after the submission of the IR to EPA for final approval. If stakeholders continue to have
concerns with the IR and 303(d) list, they should submit their comments during the next IR cycle.
• EPA has 30 days to approve or disapprove the 303(d) list after receiving DWQ’s formal submission, IR chapters, 303(d) list, categorization of non-303(d) waterbodies, public comments received and DWQ’s response to comments, delisting tables and justifications, list of approved TMDLs/pollution-control mechanisms, and GIS files of all assessment results. If EPA disapproves a state 303(d) list, EPA has 30 days to develop a new list for the state, although historically, this is not common. EPA may also partially disapprove a list because some waters have been omitted, and EPA may add these waters to the state’s list. If EPA’s final approval of the IR takes longer than the timeframe identified above, DWQ will post updates on Utah’s Integrated Report programs webpages.
• Any concerns and comments not received by DWQ through the above processes will not be addressed in the IR.
Finalizing the Integrated Report and 303(d) List
DWQ will release the following information on the Utah’s Integrated Report program webpages following
approval by EPA:
• A final version of 303(d) Assessment Methods, including the public comments received and DWQ’s
response to comments
• Final IR chapters and 303(d) lists, including public comments received, DWQ’s response to comments, all
assessment information considered and evaluated in the finalization of the IR and 303(d) list, and a GIS file
of the final assessments and 303(d) list
EPA maintains a database of state IR results and TMDL status. Additional information not available on Utah’s
Integrated Report program’s webpages may be obtained through a Government Records Access and
Management Act (GRAMA) request. GRAMA requests can be submitted at any time.
Scope of the Assessment
Waters of the State
As defined in UAC R317-1-1, DWQ characterizes waters of the state as follows:
… all streams, lakes, ponds, marshes, watercourses, waterways, wells, springs, irrigation systems, drainage
systems, and all other bodies or accumulations of water, surface and underground, natural or artificial, public or private, which are contained within, flow through, or border upon this state or any portion thereof, except
that bodies of water confined to and retained within the limits of private property, and which do not develop into or constitute a nuisance, or a public health hazard, or a menace to fish and wildlife, shall not be
considered to be "waters of the state" under this definition (Section 19-5-102).
For 303(d) assessment purposes, DWQ reports on the following waterbodies:
• Rivers and streams
• Canals as identified in site-specific standards or named in the list of waters with designated use
classifications in UAC R317-2
• Lakes, reservoirs, and ponds
21
Waterbody Types
Utah assesses surface waters of the state at the monitoring-site level and then summarizes the site-level
assessments at a larger spatial scale, the Assessment Unit scale. DWQ uses the descriptions in Table 4 to
determine appropriate assessment sites and categorize monitoring locations.

Table 4. Assessed waterbody types used for categorizing monitoring locations. Assessed Waterbody Type Description
Rivers and streams*
Perennial and intermittent surface waters are included in this type. Springs and seeps are also included in this waterbody type, provided they are flowing and connect, contribute, or are influencing water quality in a downstream river or stream.
Canals (general, irrigation, transport, or drainage)*
A human-made water conveyance with flowing water. Note: Canals are only assessed when identified in the site-specific numeric criteria in UAC R317-2-14 or are
named in the list of waters with designated use classifications in UAC R317-2-13.

Lakes, reservoirs, and ponds*
An inland body of standing fresh or saline water that is
generally too deep to permit submerged aquatic vegetation to take root across the entire body. This
type may include expanded parts of a river or natural lake, a reservoir behind a dam, or a natural or
excavated depression containing a waterbody without surface water inlet and/or outlet.
*Footnote: Sites associated with these waterbody types that have readily available and credible data are also subject to secondary reviews as described in the Secondary Review section and Appendix 2.
Assessment Units
Assessment Unit Delineation and Identification
Surface waters identified for 303(d) assessments were delineated into discrete units called assessment units
(AUs). AUs identify waters of the state assessed for support of their designated beneficial uses. Lakes,
reservoirs, and ponds are delineated as individual AUs, and their size is reported in acres. Flowing surface
waters (rivers and streams) and canals are delineated by specific rivers or one or more surface water
reaches in subwatersheds, and their size is reported in perennial stream miles.
DWQ will document any changes to the general AU delineating approach or individual assessment unit
boundaries to maintain transparent and consistent records for evaluating water quality trends. If a change
results in the removal of a waterbody from the 303(d) list, a rationale will be provided in the Integrated
Report.

Additional Guidelines for Delineating Assessment Units
DWQ follows the guidelines listed below when delineating AUs for flowing surface waters (rivers and
22
streams) of the state. The first two guidelines are fixed rules.
• AU boundaries generally follow hydrologic units, but may also be delineated to reflect beneficial use designation changes, major tributaries or other observed hydrologic or chemical changes, administrative
boundaries such as at some U.S. Forest Service boundaries, or notable road crossings as stated in water quality standards at UAC R317-2-13.
• The entire AU is within a single 8-digit USGS HUC.
• With few exceptions, each AU comprises reaches with identical designated beneficial use classifications. For example, a waterbody that has beneficial uses of Class 1C, 2B, and 3A in one portion and Class 2B and 3B in another portion would have at least two distinct AUs because of the difference in beneficial use classifications.
• Large flowing surface waters of the state, such as the Green River, Colorado River, and portions of other large rivers (e.g., the Bear River and Weber River) are delineated into "linear" or "ribbon" AUs containing no tributaries. Where a major tributary enters these rivers, or hydrological features such as dams exist, the
river is further delineated into two or more AUs.
• Tributaries and headwaters were delineated primarily using the 5th- and 6th-level HUC boundaries to define the AUs.
• Additional AUs were defined by combining or splitting 5th- or 6th-level watersheds using hydrological and ecological changes such as geology, vegetation, or land use.
• Small tributaries to larger flowing surface waters that could not be incorporated into a watershed unit are
combined into separate, unique AUs.
Individual AUs for flowing surface waters of the state are assigned a unique identification code for indexing.
Each AU identifier begins with the prefix “UT,” before the associated 8-digit HUC, followed by a 3-digit DWQ
sequential number, and finally a two-digit sequential number indicating whether the AU is the result of
resegmentation of a parent AU. Similarly, lake, reservoir, and pond AUs are identified by adding the prefix
“UT-L-” to the 8-digit HUC, followed by a 3-digit sequential number, and finally a two-digit sequential number
indicating whether the AU is the result of resegmentation of a parent AU.
Figure 1 provides an example of how DWQ uses these guidelines to delineate and identify AUs within a
major watershed. The Weber River is delineated as a linear AU from its confluence with Chalk Creek
upstream to the Wanship Dam and designated as UT16020101-017_00. South Fork Chalk Creek
(UT16020101-011_00) in the Chalk Creek watershed is delineated by combining two 12-digit HUCs
comprising the South Fork Chalk Creek sub-basin. The first AU (UT16020101-010_00) in the Chalk Creek
watershed above Echo Reservoir is delineated using the confluence of the South Fork as the upstream
endpoint. This necessitated splitting the 12-digit HUC into two AUs, one for Chalk Creek below the
confluence with South Fork (UT16020101-010_00) and another AU for Chalk Creek above the South Fork
confluence and below the Huff Creek confluence to form UT16020101-012_00. UT16020101-019_00 AU is
an example of small tributary streams that could not be combined into a hydrological based AU. These are
very small tributaries, and the Weber River is not reflective of their stream order or the habitat that they flow
through. Echo Reservoir (UT-L-16020101-001_00) and Rockport Reservoir (UT-L-16020101-002_00) are
examples of lake or reservoir AUs.
23
Figure 1. Utah Division of Water Quality assessment unit delineations.
AU Stream Mileage Estimation for Flowing Surface Waters and Canals
Flowing surface water assessments are summarized by perennial stream mileage in each assessment
category. Stream mileage within each AU is estimated using a streams GIS layer generated by the Utah
Geospatial Reference Center (UGRC). This layer was derived from the high resolution (1:24,000 scale)
National Hydrologic Dataset (NHD). Stream mileage within an AU is estimated as the sum of the lengths of all
perennial streams and canals identified in the site-specific numeric criteria in UAC R317-2-14 or named in the
list of waters with designated use classifications in UAC R317-2-13. The NHD-based layer is only used to
estimate stream mileage within an AU and is not used to define individual monitoring locations as perennial or
intermittent; or remove monitoring locations from the assessment process.
Waters Within and Shared with Other States
Though readily available data may exist from locations near Utah’s state boundaries, DWQ only assesses
monitoring sites that are within the jurisdictional boundaries of the state for 303(d) purposes. Assessment
units or sites on lands under tribal jurisdiction are not assessed in the IR. Assessed surface waters of the
state (as defined in Table 4) that flow into Utah but originate outside of Utah’s borders will be assessed using
24
DWQ monitoring locations within state boundaries. Lakes, reservoirs, and ponds that overlap with other state
jurisdictions (e.g., Lake Powell, Bear Lake, and Flaming Gorge) will be assessed using the monitoring
locations that fall within Utah state jurisdictional boundaries.
DWQ will work with neighboring states, as resources allow, on any impairments that fall close to jurisdictional
boundaries by notifying the neighboring state and/or tribe of the impairments or exceedances and available
data relevant to the impairment.

Data Quality
Credible Data Defined
All readily available data and information that are submitted to the Utah’s Integrated Report program or
obtained during the IR’s data compilation process must be of high quality to be considered for 303(d)
assessments.

Utah’s IR program defines credible data as a complete and validated data submission consisting of
• Water quality samples and field measurements (data) that are collected using appropriate quality assurance (QA) and quality control (QC) procedures, including proper documentation
• Environmental data that are representative of water quality conditions at the time of sampling
• Documented field sample collection, processing, and laboratory analyses that are documented and follow established protocols, procedures, and methods. Further information on proper adherence to these requirements is available upon request.
Utah’s IR program relies on documentation from project planners, sample collectors, and laboratories to help
ensure that data are of known quality and defensible. External entities are not obligated to collect data under
the specifications of any of DWQ's or EPA's currently established quality assurance protocols to be
considered credible, but all sources of data must meet the definition of credible data. DWQ will evaluate the
credibility of data using the criteria and documentation described in the following sections.
Please note that the definition of credible data outlined in this document is specific to Utah’s IR program. It
does not preclude other programs within DWQ (e.g., water quality standards development, TMDLs) from
using data for their own reporting, analyses, or actions based on their specific requirements
Components for Credible Data
Quality Assurance Program Plan Guidance and Example
Utah’s IR program requires that all assessment-related decisions that use data are supported by a Quality
Assurance Project Plan (QAPP). QAPPs “integrate all technical and quality aspects of a project, including
planning, implementation, and assessment.” The purpose of a QAPP is to document planning results for
environmental data operations and to provide a project-specific “blueprint” for obtaining the type and quality of
environmental data needed for a specific decision or use. The QA Project Plan documents how quality
assurance (QA) and quality control (QC) are applied to an environmental data operation to assure that the
results obtained are of the type and quality needed and expected” (EPA, 2002).
External entities may be required to provide the QAPP they relied upon for the data collection associated with
a particular submission. External entities may choose to follow one of the example QAPPs below or develop a
QAPP specific to their entity or sampling program(s).
25
Example QAPPs
• Environmental Protection Agency’s Quality Assurance Quality Program Guidance & Requirements. EPA’s
requirements and guidance documents for ensuring that all environmental data are of a known quality and defensible. Utah’s IR program encourages DWQ staff, cooperators, and all other parties interested in
submitting high quality data to the IR program to review QA/S2 and QA/G-5.
• DWQ Quality Assurance Program Planning (QAPP). DWQ’s document outlining the minimum Quality Assurance and Quality Control (QA/QC) requirements for environmental data generated by DWQ and used by most of its cooperators.
Sampling Analysis Plan Guidelines and Examples
Sampling Analysis Plans (SAPs) are the second type of documentation that Utah’s IR program requires when
compiling information for assessments and other programmatic decisions. SAPs are intended to assist
organizations in documenting the procedural and analytical requirements for projects involving the collection
of water, or other samples taken to characterize the condition, quality and designated beneficial uses of
water. It combines the basic elements of a Quality Assurance Project Plan (QAPP) and a Field Sampling
Plan.
External entities may be required to share the SAP relied upon for data collection associated with a particular
submission. External entities may choose to follow the format of one of the example SAPs below when
developing a SAP specific to their sampling program(s).
Example SAPs
• EPA’s Sampling Analysis Plan Guidance & Requirements.
• DWQ’s recommended Sampling Analysis Plan Requirements. These requirements are currently used
by DWQ and its cooperators. This document contains information on what DWQ looks for in a SAP
(see Appendix 1).
Standard Operating Procedures Guidelines and Examples
Standard Operating Procedures (SOPs) are documented procedures that describe the routine operations of a
monitoring program in full detail. Utah’s IR program requires SOPs as part of data submission packages to
ensure consistency and comparability across sampling techniques from disparate data sources.
External entities may be required to share the SOPs relied upon for data collection associated with a
particular submission. External entities may choose to follow the example SOPs below or develop SOPs
specific to their sampling program(s).
Example SOPs
• EPA’s Guidance for Preparing Standard Operating Procedures (G-6). EPA’s guidance for developing and
providing the necessary documentation when generating an SOP. DWQ recommends referring to
EPA’s guidance if not using DWQ’s SOP.
• DWQ Standard Operating Procedure. DWQ generates SOPs for any procedure that becomes routine,
even when published methods are utilized. The use of SOPs ensures data comparability, defensibility,
and accuracy, and reduces bias. DWQ SOPs available on the website include macroinvertebrate
collection, calibration, maintenance, and use of multiparameter water quality sondes, chlorophyll-a
sampling, harmful algal bloom collection and identification, water chemistry and E. coli sample
collection, among
Sampling Observations and Laboratory Comments
26
Utah’s IR program requires documentation of field conditions that may affect data quality or laboratory
comments on QA/QC issues encountered during analysis. The credible data matrices included in Table 5 -
Table 9 describe additional sampling and laboratory observations and comments required by Utah’s IR
program.
Monitoring Location Information
DWQ must review all monitoring location information associated with datasets to assess waterbodies against
the numeric criteria assigned in UAC R317-2-14. This process involves validating the location’s geospatial
information in GIS, assigning beneficial uses to DWQ-validated locations, and merging monitoring locations
and their associated data where locations are representative of the same waterbody or segment. Information
that must be included with a monitoring location measurement:
• Monitoring Location ID (organization's unique identifier for the sample site)
• Waterbody type description
• Monitoring location site description
• Monitoring location, latitude/longitude measurements
A monitoring location and its associated data will not be included in the assessment if DWQ’s geospatial
review of the monitoring location information finds insufficient or inaccurate information (e.g., it cannot be
mapped or is improperly recorded by the sampler in the field).
Credible Data Matrices
DWQ will consider the scientific rigor of the sampling information and measurements associated with sites
where beneficial uses can be assigned to a DWQ-validated monitoring location. DWQ uses a data-type–
specific, credible-data matrix to assess the validity of the sampling and analytical protocols associated with a
sample measurement, As noted in the credible-data matrices, each credible-data matrix considers the field
and laboratory QA/QC protocols, sampling and laboratory methods, analytical detection or instrumentation
limits, and field observations associated with a sample measurement. DWQ assigns a grade level (A–C) to
the associated sample measurement(s) based on the level of information provided and the strength of the
metadata associated with the sample measurement.
DWQ considers measurements that receive an A or B grade to be of high quality and will consider and use
them to assign an EPA-derived assessment category to a waterbody (i.e., the IR’s 305(b) and 303(d)
assessments). Measurements that receive a C grade are considered to be of insufficient quality for
assessment and 303(d) listing purposes. Details on the required data quality criteria for inclusion in the IR and
use by Utah’s IR program are included in Tables 5-9.
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Table 5. Data validation criteria for water quality field grab sample parameters.

Data Quality Grade
Quality Assurance

Essential Metadata1

Calibration Documentation

Field Documentation

Flow Data
Calibration: Water Temperature Methods*

Calibration: pH Methods*
Calibration: Dissolved Oxygen, Percent Saturation for Calibrated Meter*
Calibration: Dissolved Oxygen, Concentration Methods for Calibrated Meter*

A
QAPP, SAP(s), and SOP(s) or equivalents are available for DWQ review if requested
Essential metadata is included with the data submission.
Available for DWQ review if requested for all field parameters

Available for DWQ review if requested
Submitted or available for DWQ review if
requested
Checked against NIST
A ≤ ± 0.2 ºC
Calibrated pH Probe A ≤ ± 5%
0-200 %Sat: A ≤ ± 6%
0-8 mg/L: A ≤ ± 0.1mg/L > 8mg/L:
A ≤ ± 0.2 mg/L
B
QAPP, SAP(s),
and SOP(s) or equivalents are available for DWQ review if requested
Essential metadata is provided to DWQ upon request.
Available for DWQ review if requested, for field parameters
Unavailable
Not submitted or unavailable
A ≤ ± 0.2 ºC Calibrated pH Probe A ≤ ± 5%
0-200 %Sat: A ≤ ± 10%
0-20 mg/L: A ≤ ± 0.2 mg/L
C
QAPP, SAP, or SOP is unavailable Not Submitted
Essential metadata is missing from the data submission and is unavailable.
Unavailable
Unavailable
Not submitted or unavailable
A ≥ ± 0.5 ºC
OR not a calibrated meter, missing, or rejected data
Not a calibrated meter, missing, or rejected data
Not a
calibrated meter, missing, or rejected data
Not a calibrated meter, missing, or rejected data
1 Essential metadata elements are sample location (latitude/longitude), waterbody type, sample date and time, parameter name, result value and unit. *Footnote: A = accuracy, values based on technical specifications of commonly used YSI, Hydrolab, and In-Situ AquaTROLL sondes.

Table 6. Data validation criteria for water quality high frequency dissolved oxygen data.
Data
Quality Grade
Quality Assurance
Quality Assurance Project Plan (QAPP)

Essential Metadata1
Calibration Documentation
Data QA/QC
Information or Report

Field Documentation

Flow Data
Calibration: Dissolved Oxygen*, Percent Saturation for Calibrated Meter
Calibration: Dissolved Oxygen*, Concentration Methods for Calibrated Meter
A QAPP, SAP(s), and SOP(s)
or equivalents are available for DWQ review if requested
Essential metadata is included with the data submission.
Mandatory-calibration record(s) (e.g., field records of calibration and/or fouling)
Documentation describing the QA/QC
process on the raw data
All pertinent deployment data (i.e., information
necessary for interpreting data)
Submitted or available for DWQ
review if requested
0-200%:
A ≤ ± 6%
0-8 mg/L: A ≤ ± 0.1 mg/L
> 8mg/L: A ≤ ± 0.2 mg/L
B
QAPP, SAP(s), and SOP(s)
or equivalents are available for DWQ review if requested
Essential metadata is
provided to DWQ upon request.
Mandatory-calibration record(s) (e.g., field
records of calibration and/or fouling)
Documentation describing the QA/QC
process on the raw data
All pertinent deployment data (i.e., information
necessary for interpreting data)
Not submitted or unavailable
0-200%: A ≤ ± 10%
0-20 mg/L:
A ≤ ± 0.2 mg/L
C QAPP, SAP, or SOP is unavailable
Essential metadata is missing from the data submission and is unavailable. Unavailable Unavailable Unavailable Not submitted or unavailable Missing, or rejected data

1 Essential metadata elements are sample location (latitude/longitude), waterbody type, sample date and time, parameter name, result value and unit. *Footnote: A = accuracy, values based on technical specifications of commonly used YSI, Hydrolab, and In-Situ smarTROLL sondes.
Please note: Raw and QA/QC data records must be submitted to qualify for consideration in 303(d) assessments.
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Table 7. Data validation criteria for water quality chemistry grab sample parameters. Data Quality Grade
Quality Assurance Project Plan (QAPP)
Essential Metadata1 Laboratory Method Detection Limits Lab Certification QC Data Laboratory Comments Field Documentation Metals* Organics* Inorganics*

A

QAPP, SAP(s), and SOP(s) or equivalents are available for DWQ review if requested

Essential metadata is included with the data
submission.

Standard Methods

Below applicable water quality standard

Utah Bureau of Laboratory Improvement certification, NELAC, or equivalent
Available for DWQ review if requested

Laboratory Comments Associated with Sample

Available for DWQ review if requested
Chronic: Aluminum submitted with Ca and Mg OR Lab Hardness and field pH; Cadmium, Chromium (III), Copper, Lead, Nickel, Silver, and
Zinc submitted with Ca and Mg OR Lab Hardness

Pentachlorophenol submitted with field pH

Total Ammonia as N submitted with field pH or field
Temperature

B
QAPP, SAP(s), and
SOP(s) or equivalents are
available for DWQ review if requested
Essential
metadata is provided to
DWQ upon request.

Standard Methods

Below applicable water quality
standard

Documentation of laboratory procedures

Available for DWQ review if requested
Laboratory Comments Associated with Sample

Unavailable
Chronic: As above, but Aluminum submitted without Hardness or field pH will be assessed at 750 ug/l; As above, but samples submitted without Ca, Mg, or Lab Hardness **

Pentachlorophenol submitted without
field pH
Total Ammonia as N submitted without field pH or field Temperature

C

QAPP, SAP, or SOP is unavailable
Essential metadata is missing from the data submission and is unavailable.
Missing or Non- Standard Methods

Above applicable
water quality standards

No certification or
laboratory documentation

Unavailable

No Laboratory Comments

Unavailable
Chronic: As above, but Aluminum without Hardness or field pH will not be assessed;

Pentachlorophenol
submitted without field pH
Total Ammonia as N submitted without field pH or field Temperature
1 Essential metadata elements are sample location (latitude/longitude), waterbody type, sample date and time, parameter name and fraction, parameter units, analytical method, result value or non-detect limitation, and laboratory name. *Footnote: Please also refer to UAC R317-2 to confirm that all the necessary data is submitted to DWQ so correction factors and equations may be fully calculated for 303(d) assessment purposes. **Footnote: Please refer to the 303(d) Assessment Methods for corrections to assessment due to missing values of hardness or pH.
29
Table 8. Data validation criteria for macroinvertebrate data. Data Quality Grade Quality Assurance Project Plan (QAPP) Essential Metadata1 Field Documentation Qualified taxonomy lab
A
EPA-approved Lab QAPP available for DWQ review if requested; SAP and SOP or equivalents available for DWQ review if requested
Essential metadata is provided to DWQ upon request.
Available for DWQ review if requested Required
B
Lab QAPP or equivalent is available for DWQ review if requested; SAP and SOP or equivalents available for DWQ review if requested
Essential metadata is provided to DWQ upon
request.
Unavailable Required
C QAPP, SAP, or SOP is unavailable Essential metadata is missing from the data submission and is unavailable. Unavailable Unavailable
1 Essential metadata elements are sample location (latitude/longitude), waterbody type, sample date and time, parameter name and fraction, analytical method, result value and unit, and laboratory name.
Table 9. Data validation criteria for Escherichia coli (E. coli) data.

Data Quality Grade Quality Assurance Essential Metadata1 EPA Approved Method Lab Documentation QA/QC
A QAPP, SAP(s), and SOP(s) or equivalents are available for DWQ review if requested
Essential metadata is provided to
DWQ upon request. IDEXX Colilert Bench Sheet Present and Complete Information on holding time, incubation*, and expiration dates provided.
B
QAPP, SAP(s), and SOP(s) or
equivalents are available for DWQ review if requested
Essential metadata is provided to
DWQ upon request. IDEXX Colilert or EasyGel Bench Sheet Present, incomplete, or
not available Not provided
C QAPP, SAP, or SOP is unavailable
Essential metadata is missing from
the data submission and is unavailable. IDEXX Colilert or EasyGel Unavailable Not provided
1 Essential metadata elements are sample location (latitude/longitude), waterbody type, sample date and time, parameter name and fraction, analytical method, result value and unit, and laboratory name. *Footnote: "incubation" refers to data and information that is recorded on DWQ's E. coli bench sheets and relates to time and temperature (i.e., time samples were placed in and taken out of the incubator and the temperature of the incubator when samples were placed in and taken out of it). For an example of how DWQ records this information, please refer to Appendix 1 of DWQ's Standard Operating Procedure for Collection, Handling, and Quantification of Escherichia coli (E. coli) Samples.
30
Data Submission Process Type of Data to Submit
As referenced in 40 CFR 130.7(b)(5), Utah’s IR program considers all existing and readily available data as
defined in Table 3. Both quantitative and qualitative data may be used to evaluate whether physical, chemical,
and biological characteristics of a waterbody are sufficient to support that waterbody’s designated uses.
However, based on the type of data submitted to or obtained by DWQ during Utah’s IR program’s Call for
Data,, some of these data may not be appropriate for assessments. DWQ considers several quantitative and
qualitative types of data described in Table 10 for water quality assessments and analyses as recommended
in EPA’s July 29, 2005, guidance (EPA, 2005).

Table 10. Summary of data types considered by Utah’s IR program.
Utah’s IR program Data Uses Quantitative Data Qualitative Data Other

305(b) and 303(d) Assessments (Grade A and B Data in credible data matrices)
(1) Assessment parameters contained in Utah Water Quality Standards (UAC R317-2) and Safe Drinking Water Act Standards, (2) segment-specific ambient monitoring of analytical, physical, and/or biological conditions, (3)simple dilution calculations, and (4) human health/consumption closures, restrictions, and/or advisories
(1) Observed effects
(e.g., fish kills), (2) complaints and
comments from the public, and (3) human
health/consumption closures, restrictions, and/or advisories

Landscape analysis (when applicable)
Monitoring Planning and Training (Grade C Data in credible data matrices)

Refer to the credible data matrices presented in Tables 5-9 above

Refer to the credible data matrices presented in Tables 5-9 above
(1) Landscape analysis (when applicable), (2)
technical reports, (3) white papers, (4) articles from referred journals, and (5) other scientific publications
Period of Record
DWQ uses water years to define the period of record and uses the same definition of water years as the U.S.
Geologic Survey (USGS). USGS defines the water year as the 12-month period between October 1 and
September 30 of the following year. For the 2026 IR, the period of record is October 1, 2018, to September
30, 2024, (water years 2019-2024).
Data and information from the IR’s period of record are considered to be most reflective of the current
conditions of a waterbody. DWQ will analyze and assign EPA-derived assessment categories to the assessed
waterbodies from this record period, provided the data meet the sampling, and analytical considerations and
protocols outlined in this document (see Table 1).
Older Data and Information
DWQ will not consider data and other information older than the period of record in the current IR and 303(d)
list unless the data are used to support a secondary review of an impairment determination. Instead, DWQ
31
will encourage the data submitter to collect newer information and submit those data and information in future
calls for data. The IR’s period of record does not preclude DWQ from using older or longer-term datasets for
programs other than assessments (e.g., water quality standards development, TMDLs, etc.).
Newer Data and Information
Quantitative and qualitative data types that are considered in 303(d) assessments but are collected or
represent conditions after the closing date specified in the above period of record will not be considered in the
current reporting cycle. DWQ does not include these newer datasets because of the time required to compile
data, perform data quality checks, format data from different sources, assess, review assessments, and
generate the IR and 303(d) for public comment by April 1 of even-numbered years.
Data Submission Tools
Data should be submitted in a form that is compatible with the Utah’s IR program’s existing data-management
and QA capabilities. Please refer to Table 3 for more information on how to submit data for consideration in
the IR.

Data Preparation for Conventional and Toxic
Assessments for All Waters
DWQ compiles all high quality data within the period of record following the readily available and credible data
reviews, and then standardizes, validates, and prepares the data for assessments. To assist reviews and
increase transparency to reviewers, DWQ uses a series of comments and flags rather than altering raw data and
accompanying metadata. Though High Frequency Dissolved Oxygen (DO) and E. coli assessments are
considered conventional assessments (see Table 11), these parameters have data preparation protocols that are
unique to those datasets. Please refer to the High Frequency and E. coli assessment sections of this document
for more details. Results below Detection Limits
Environmental chemistry laboratories often report sample results as below their detection limit for a given
analytical method. These limits are variously reported as minimum detection limit, minimum reporting limit,
and/or minimum quantitation limit. The reported result value or a value of 0.5 times the lowest reported
detection limit for sample results below detection is applied for purposes of the assessment. For laboratory
result values that are empty and have detection limits higher than the water quality criteria in UAC R317-2-
14; these flagged data records are not considered in the assessment.
Duplicate and Replicate Results
Datasets often contain duplicate and replicate sample results due to QA/QC procedures, reporting errors, or
sampling design. In these cases, a single daily value is determined by accepting the highest result for
parameters with not-to-exceed criteria in UAC R317-2-14, or the lowest reported value for parameters with
minimum criteria in UAC R317-2-14. All data are retained in the assessment dataset and flagged as rejected
because of replicate or duplicate values.
32
Initial Assessment: Monitoring Location Site Level
DWQ determines attainment or nonattainment of numeric standards by assessing credible data at the
monitoring location site level against the numeric criteria in UAC R317-2-14. DWQ developed this protocol
because individual assessments offer a more direct measure of the support or non-support of water quality
standards in UAC R317-2.
Multiple parameter assessments at an individual monitoring location and results from multiple monitoring
locations within the same AU are summarized and combined using the procedures outlined in the
Determinations of Impairment: All Assessment Units section of this report.

Assessments Specific to Rivers, Streams, and
Canals
Conventional Parameter Assessments
DWQ currently assesses five parameters within UAC R317-2-14 as conventional parameters and assesses
them against the beneficial-use specific criteria established in UAC R317-2. Several waterbodies with
conventional numeric criteria have site-specific standards articulated in self-explanatory footnotes within
DWQ’s surface water standards (UAC R317-2-14). Site-specific standards that require further clarification for
303(d) assessment purposes are noted and explained in Table 11. Sites that do not meet water quality
standards as described below are not supporting of beneficial uses for 303(d) assessment purposes.

Table 11. Conventional parameters and associated designated uses as identified for assessment purposes.

Parameters Designated
Use Notes

DO*

Aquatic life
DO measurements are assessed against the minimum, 7-day average, and 30-day average criteria in UAC R317-2-14. Grab samples are assessed following the processes in Figure 2 for rivers and streams and the Assessments Specific to Lakes, Reservoirs, and Ponds sections of the methods. High frequency DO datasets are assessed following the processes in Figures 3-5. Note: DWQ will assess against early life stage (ELS) criteria where ELS presence has been determined in a specific waterbody. Site specific standards are used for assessment where they have been developed. Maximum temperature* Aquatic life Some site-specific standards are used for assessment purposes. If available,
high frequency temperature datasets may be used in the secondary review process to ensure that grab samples are representative of the maximum
temperature observed under typical site conditions.
pH* Domestic, Recreation, Aquatic life Criteria are identical across uses.
33
Parameters Designated Use Notes

Total dissolved solids (TDS)**

Agriculture
Many site-specific standards are used for assessment purposes. The following examples clarify how site-specific standards are used for 303(d) purposes: (1) For South Fork Spring Creek from the confluence with Pelican Pond
Slough Stream to U.S. Route 89, two seasonal assessments are not performed. Instead, each sample is compared to the monthly corrected criteria in the footnote in UAC R317-2. (2) Ivie Creek and its tributaries from the confluence with Muddy Creek to the confluence with Quitchupah Creek. If TDS exceeds the site-specific standard, the site is not meeting site-specific criteria. If TDS is not
exceeding, total sulfate is assessed. (3) Quitchupah Creek from the confluence with Ivie Creek to Utah State Route 10: If TDS exceeds the site-specific standard, it is not meeting site- specific criteria. If TDS is not exceeding, total sulfate is assessed. (4) Blue Creek and tributaries, Box Elder County, from Bear River Bay, Great Salt Lake to Blue Creek Reservoir. The only site to be assessed
within this area is 4960740. (All other sites within this area description will not be assessed for TDS).
Sulfate**
Agriculture
Site-specific standard associated with sulfate for the following areas: (1) Ivie Creek and its tributaries from the confluence with Muddy Creek to the confluence with Quitchupah Creek: When TDS is not exceeding site- specific criteria and total sulfate exceeds site-specific criteria, the area does not meet water quality standards.
(2) Quitchupah Creek from the confluence with Ivie Creek to Utah State Route 10: When TDS is not exceeding site-specific criteria and total sulfate exceeds site-specific criteria, the area does not meet water quality standards. *Footnote: Indicate that assessments are performed from field measurement only. **Footnote: Indicate that assessments are performed from lab measurements only.
Grab Sample Assessments
A minimum of 10 samples for conventional parameters are required to determine if a site is meeting or not
meeting water quality standards (Figure 2). Where locations have sufficient sample sizes of 10 or more, an
exceedance percentage is calculated for each applicable beneficial use by dividing the number of samples
exceeding the numeric criterion by the total number of samples. If the calculated percentage is less than or
equal to 10%, the site is supporting its beneficial use. If the calculated percentage is greater than 10%, the
site is not supporting its beneficial use. This assessment is repeated for each beneficial use and numeric
criterion. In the case of waterbodies with site-specific standards for TDS and sulfate, both criteria must be met
or the waterbody will be listed as not supporting its agricultural use.
34

Figure 2. Overview of the assessment process for conventional parameters using grab sample data.
High Frequency Assessments for Dissolved Oxygen
Data Preparation
High frequency data are often screened and corrected to account for sensor drift, calibration shift, strange
anomalous points, and battery issues before data analysis and interpretation begins. These data corrections
are particularly important for dissolved oxygen (DO) sensors because they are subject to bio-fouling,
especially in nutrient-rich water where they have the higher potential to become covered in algal growth.
When bio-fouling occurs, it results in erroneous logger measurements or sensor drift. DWQ will use
corrected high frequency data as documented by the data submitter for assessments. DWQ will contact the
data submitter for clarification and additional information if it determines additional data validations may be
required.
Data sufficiency
High frequency data must capture complete days to ensure daily minima are captured and daily averages can
be accurately calculated. DWQ defines a complete day as a calendar day (i.e., 12:00 a.m. – 11:59 p.m.) in
which at least one measurement is made in each hour. Incomplete days will not be included in the high
35
frequency DO assessment.
36
Assessment Process
A daily minimum and daily average are calculated for each complete day in a dataset. Moving 7- and 30-day
averages are then calculated from the daily averages for each 7- or 30-day period within the dataset. These
values are then compared to the applicable daily minimum, 7-day average, and 30-day average criteria to
determine use impairment or support.
A site does not meet the daily DO minimum criterion if the percentage of total daily minima that fall below the
applicable standard is greater than 10% within the period of record (Figure 3).

A site does not meet the 7-day average criterion if the percentage of 7-day averages that fall below the
applicable standard is greater than 10% within the period of record (Figure 4).
Figure 3. Overview of the assessment process for the minimum dissolved oxygen, daily minimum, using high frequency data.
37
Figure 4. Overview of the assessment process for the minimum dissolved oxygen, 7-day averages using high frequency data.

38
A site does not meet the 30-day average criterion if the percentage of 30-day averages that fall below the
applicable standard is greater than 10% within the period of record (Figure 5).
A site is considered not supporting if it is not meeting either of the daily minimum, 7-day average, or 30-day
average criteria. A site is considered fully supporting if 10% or fewer exceedances are observed for all three
criteria. This process (Figure 3 – Figure 5) is repeated until each beneficial use has been assessed.
Analyzing Multiple DO Datasets at a Site
DWQ assesses grab and high frequency data independently during the initial assessment of DO at a site and
reviews these assessments in the context of one another during the secondary review for determining
impairment. These processes are discussed in greater detail in Determinations of Impairment: All Assessment
Units
Figure 5. Overview of the assessment process for the minimum dissolved oxygen, 30-day averages, using high frequency data.
39
Nutrient Assessments Specific to Headwater Streams
Utah’s Numeric Nutrient Criteria (NNC) require consideration of both ambient nutrient concentrations and
ecological response data for headwater streams, which are defined as streams where antidegradation
category 1 or 2 protections have been established (UAC R317-2-3). Generally, this includes streams above
United States Forest Service (USFS) boundaries—about 50% of all perennial streams statewide.
Support of Aquatic Life Uses
The NNC applicable to aquatic life include two thresholds for total nitrogen (TN) and total phosphorus (TP)
based on the arithmetic average of a minimum of four samples obtained during the growing season (UAC
R317-2-14.8). The growing season is defined by the NNC as the period of algal growth through senescence.
For assessment purposes, DWQ assumes that the growing season includes the months of June through
November, although this may be lengthened where additional information demonstrates that a longer period
of growth is warranted.
The arithmetic average of TN or TP, derived from four or more growing season samples, is used to place
headwater streams into one of three enrichment tiers (Table 12). Lower criteria thresholds of 0.4 mg/L TN and
0.035 mg/L TP differentiate between low and moderate enrichment streams. Higher thresholds of 0.80 mg/L
TN and 0.080 mg/L TP differentiate between moderate and high enrichment streams. The higher of TN or TP
enrichment tiers is used to determine whether or not nutrient enrichment has degraded aquatic life uses at a
site.
Moderate enrichment streams, with average nutrient concentrations between the upper and lower thresholds,
require additional measures of ecological condition to determine whether or not a headwater stream is
attaining the NNC water quality standards (Table 12). Nutrients can degrade aquatic life uses via mechanisms
related to increased growth of plants/algae (autotrophs) and/or microbes/fungi (heterotrophs). In the case of
plant/algae growth, two ecological responses are not-to-be-exceeded at any headwater stream: (1) a daily
gross primary production (GPP) rate higher than 6 g O2/m2/day or (2) an aerial percent filamentous algae
cover exceeding 1/3 of the stream bed. Adverse heterotrophic responses are addressed using ecosystem
respiration (ER), which measures the net metabolic activities of all stream biota and is used to understand
linkages among microbes/fungi, nutrients, and aquatic life uses. NNC establishes a not-to-be-exceeded rate
for ER of 5 g O2/m2/day. Any site where TN or TP falls between the NNC thresholds is categorized as not
supporting its aquatic life uses if any of the three responses exceeds the adverse effect thresholds, even if a
complete set of responses is not available (Table 13). However, a moderately enriched stream site must have
all three response parameters collected and occurring below their adverse effect thresholds to obtain a full
support assessment for the site. If any response parameters are unavailable despite other response
parameter(s) meeting criteria, the site will be assessed as insufficient data (3A) and DWQ will prioritize the
data collection necessary to make a site assessment.
Any site where the growing season average of both TP and TN falls below the lower NNC thresholds (lowest
enrichment tier) is considered to be supporting aquatic life uses with respect to nutrient enrichment (Table 13)
provided that all three ecological responses have been measured and fall below the threshold that
demarcates degraded conditions. If any response parameters are above their degraded condition threshold,
the site will be assessed as impaired (Category 5)
At the other end of the enrichment gradient, any site where the average TN or TP concentration exceeds the
upper NNC threshold (high enrichment tier) is categorized as threatened unless degradation is confirmed by
an ecological response, in which case it is considered impaired (not supporting aquatic life uses). Threatened
40
AUs are designated as category 5 due to highly enriched conditions, but DWQ commits to more thoroughly
evaluate the AU for adverse nutrient-related responses.
41
Table 12. Numeric Nutrient Criteria and Associated Ecological Responses (Bioconfirmation Criteria) to Protect Aquatic Life Uses in Antidegradation Category 1 and 2 (UAC R317-2-12) Headwater Perennial Streams.
Nutrient Enrichment Level Summertime Average Nutrients Ecological Response Assessment Notes

Low

TN < 0.40a,b

TP < 0.035a,b
Fully supporting biological uses if the average of ≥ 4
summertime samples is below the specified nutrient concentration of either TN and TP unless ecological
responses specified for moderate enrichment streams are exceeded. Sites with fewer samples will not be assessed for nutrients.

Moderate

TN 0.40–0.80a

TP 0.035–0.080a
Plant/Algal Growthc< 1/3 or more filamentous algae coverd,e OR
GPPc of < 6 g O2/m2/day OR Plant and Microbial Growth ERc < 5 g O2/m2/day
Headwater streams within this range of nutrient concentrations will be considered impaired (not supporting for nutrients) if any response exceeds defined thresholds. Streams without response data will be listed as having insufficient data and prioritized for additional monitoring if either TN or TP falls within the specified range.

High

TN > 0.80a,b

TP > 0.080a,b
Streams over these thresholds will initially be placed on Utah’s Section 303(d) list as threatened.
Threatened streams will be further evaluated using additional data such as nutrient responses, biological assessments, or nutrient-related water quality criteria (e.g., pH and DO) both locally and in downstream waters.
Notes: Criteria would be applicable unless more restrictive total maximum daily load (TMDL) targets have been established to ensure the attainment and maintenance of downstream waters. DO = dissolved oxygen, ER = ecosystem respiration, GPP = gross primary production, TN = total nitrogen in mg/L, and TP = total phosphorus in mg/L. a Seasonal average of ≥ 4 samples collected during the summertime growing season (June 1–September 30) will not be exceeded. Sites will be assessed using the higher of TN and TP threshold classifications. b Response data, when available, will be used to assess aquatic life use support or as evidence for additional site-specific investigations to confirm impairment or derive and promulgate a site-specific exception to these criteria. c Daily whole stream metabolism obtained using open-channel methods. Daily values are not to be exceeded on any collection event. d Filamentous algae cover means patches of filamentous algae > 1 cm in length or mats > 1 mm thick. Daily values are not to be exceeded at any time during the growing season (June 1–September 30). e Quantitative estimates are based on reach-scale averages with at least three measures from different habitat units (i.e., riffle, run) made with quantitative visual estimation methods. f Excluded waters identified in UAC R317-2-13.2 (c).
42
Table 13. Decision Matrix That Will Be Used to Assess Support of Headwater Aquatic Life Uses for Nutrient-related Water Quality Problems
Ecological Responses
Nu
t
r
i
e
n
t

D
a
t
a

(
T
N

or

T
P
)

No Data < All Criteria > Any Criterion
No Data or < 4 Samples Not Assesseda Not Assesseda Impaired (5)b
< Low Threshold Not Assesseda Fully Supporting (1 or 2)d,f Impaired (5) b,e
Between Lower and Upper Threshold Insufficient Data (3A)c Fully Supporting (1 or 2)d,g Impaired (5)
Above Upper Threshold Threatened (5)f Threatened (5)e,f Impaired (5)

Note: Associated Integrated Report categories are in parentheses.
aThere are insufficient nutrient-related data to assess whether or not aquatic life uses are supported; however, aquatic life uses may be
assessed with other water quality parameters.
bSites where an ecological response threshold has been exceeded, but the lower TN and TP thresholds have not will be listed as impaired on the basis of a biological assessment; cause will be listed as unknown pending follow-up investigations.
cSites where TN or TP fall below the upper threshold, but above the lower threshold, and lack measures for at least one response variable will
not be assessed with respect to nutrients. These sites will be prioritized for follow-up monitoring.
dThe integrated report distinguishes between sites where at least one parameter has been evaluated for all uses (Category 1) and sites where
some uses are supported, and other uses are either not supported or not assessed (Category 2). eSites where nutrient and ecological response data are in conflict may be candidates for site-specific criteria.
fSites below the both lower TN and TP thresholds with at least one response below the lower threshold will be considered to be fully
supporting aquatic life uses unless another nutrient-related criterion (e.g., pH, DO) suggests otherwise. Sites without at least one measured
response are not assessed.
gSites between the lower and upper threshold require all three response parameters to be considered fully supporting with respect to nutrient
enrichment.
43
Support of Recreational Uses
Excessive nutrients can also degrade recreational uses. To protect these uses in headwater streams the NNC
establish a not-to-be-exceeded benthic algae concentration of 125 mg/chlorophyll-a (chl-a)/m2, or the
equivalent 49 g ash free dry mass (AFDM)/m2 (UAC R317-2-14.7). A site where any reach-scale biomass
value exceeds either threshold will be categorized as not supporting recreational uses (Figure 6).

Figure 6. Overview of the assessment process to determine support of recreational life uses based on nutrient enrichment in headwater streams.
44
Narrative Standards: Biological Assessments
Utah’s beneficial uses for aquatic life require the protection of fish (cold water or warm water species) and
the organisms on which they depend (UAC R317-2-6.3). DWQ uses an empirically based model that directly
assesses support of aquatic life uses by quantifying the integrity of macroinvertebrate assemblages. The
biological integrity of sites is evaluated as a numerical index (Hawkins, 2006; Hawkins et al. 2010) calculated
using a comparison of the biological composition observed at a focal site against a subset of ecologically
similar reference sites (Hughes et al.,1986; Suplee et al.,2005).
River Invertebrate Prediction and Classification System Models
DWQ uses the River Invertebrate Prediction and Classification System (RIVPACS) model approach to
quantify biological integrity (Wright, 1995). RIVPACS is a classification of freshwater sites based on
macroinvertebrate fauna used to predict invertebrate taxa expected to occur under reference conditions.
DWQ’s RIVPACS model was verified and reconstructed by the USU BugLab. RIVPACS models compare the
list of taxa that are observed (O) at a site to the list of taxa expected (E) with the least-human-caused
disturbance for a similar site to quantify biological condition. Predictions of E are obtained empirically from
reference sites that together are assumed to encompass the range of ecological variability observed among
streams in the region where the model was developed. In practice, these data are expressed as the ratio O/E,
the index of biological integrity (Figure 7). More information on Utah’s RIVPACS model can be found on the
DWQ website.

Figure 7. A hypothetical example of O/E as a standardization of biological assessments.
45
Assessing Biological Use Support
DWQ does not have numeric biological criteria. However, DWQ has narrative biological criteria (UAC R317-2-
7.3) that specify how quantitative model outputs are used to guide assessments. A systematic procedure to
make the narrative assessments as rigorous as possible was devised to use the RIVPACS model O/E values
to determine aquatic life beneficial use support (Figure 8). This biological assessment, using RIVPACS O/E
values, provides crucial information on the condition of aquatic life and contributes to the overall
characterization of each AU as fully supporting or not supporting its designated beneficial uses.

Although many AUs contain a single biological monitoring location, some AUs contain multiple sites. In such
instances, DWQ staff examines available data to determine if multiple sites in an AU score similarly. When
comparisons suggest that sites in one AU are ecologically similar, O/E scores from all sites in an AU are
averaged for assessment purposes, provided that conclusions of biological condition are similar. If O/E scores
differ appreciably among multiple sites in an AU, DWQ will investigate possible explanations for such
discrepancies (see the Assessment Unit Re-segmentation discussion for more information on that process).
Figure 8. Decision tree for making biological assessment decisions.
46
Additionally, if only one site is sampled in an AU, it is examined to determine whether it is an appropriate
representation of the AU.
To translate the O/E values into assessment categories, it is necessary to devise thresholds, or O/E scores
that indicate whether or not a site is meeting biological beneficial uses (Table 14). The 10th and 5th
percentiles of reference sites were used for these assessments. The data used for the current assessment
calculate the threshold based on 5th percentile at 0.69, whereas the 10th percentile is 0.76. These thresholds
will provide the bounds according to sample strength. The data are averaged across six years since the most
recent year of available data. Multiple years are preferred for assessments because O/E scores can vary from
year to year and assessments are based on average conditions. Assessments based on the average
condition of three or more samples reduce the probability of making an error of biological beneficial-use
support as a result of an unusual sampling event (e.g., following a flash flood, or a sample that was preserved
improperly).

Table 14. Beneficial use support determination for O/E values obtained from different sample sizes. Sample Size O/E Threshold Use Determination Comments
≥ 1 sample collected over 6 years Mean O/E score ≥ 0.76 Fully Supporting Threshold based on 10th percentile of reference sites
≥ 3 samples collected over 6 years Mean O/E score < 0.76 Not Supporting Threshold based on 10th percentile of reference sites
< 3 samples Mean O/E score ≥ 0.69–≤
0.76 Insufficient Data with Exceedances
Lower threshold based
on 5th percentile of reference sites
< 3 samples 2 O/E scores < 0.69 Not Supporting Threshold based on 5th percentile of reference sites
< 3 samples 1 O/E score < 0.69 Insufficient Data Threshold based on 5th percentile of reference sites
AUs not meeting biological thresholds will be assessed as not supporting. Assessments of more than three
samples with average O/E scores of greater than or equal to 0.76 have a low probability of being misclassified
as nonsupport. Alternatively, assessments with fewer than three samples with an average O/E score of less
than 0.69 have a 5% probability of being misclassified as nonsupport. To ensure that one sample was not
incorrectly misapplied, at least two samples with a score of 0.69 or less will be required to consider an AU not
meeting the aquatic life use. Assessments with fewer than three samples that have a mean O/E score of
greater than or equal to 0.69 and less than 0.76 will be placed in Category 3 (insufficient data and information
with exceedances), which indicates that there are insufficient data to make an assessment. All sites listed as
Category 3 with exceedances will be given a high priority for future biological monitoring.
47
Assessments Specific to Lakes, Reservoirs,
and Ponds
Assessment Overview
Lakes, reservoirs, and ponds are classified by basin in UAC R317-2-13.12, with the accompanying tables
listing their designated beneficial uses. Waterbodies not specifically listed are assigned beneficial uses by
default to the classification(s) of the tributary stream(s). Numeric water quality criteria for both toxic and
conventional parameters are assigned for each designated use in UAC R317-2-14, Deeper lakes naturally
stratify thermally, which affects how conventional water quality parameters are assessed (UAC R317-2-14), so
each waterbody is evaluated for thermal stratification and assessed appropriately.
Utah lake and reservoir assessments are divided into two tiers:
Tier I
The Tier I assessment is the preliminary determination of beneficial use support for drinking water use (Class
1), recreational use (Class 2), aquatic life (Class 3), and agricultural (Class 4), classes based on
conventional parameters such as DO, temperature, and pH, toxic parameters, and E. coli. When Tier I data
are not available, DWQ may rely on Tier II data to make an initial assessment. The waterbody will be
classified as mixed or stratified based on the depth profile information when considering aquatic life use
support within this tier. If it is a stratified waterbody, the evaluation of conventional parameters will follow the
protocol designed to evaluate the sufficiency of aquatic life habitat. If the waterbody is mixed, it will follow
the assessment protocol that evaluates the entire depth profile.
Tier II
The Tier II assessment looks further into specific weight of evidence criteria (trophic state index [TSI], fish
kills, and algal composition) through secondary reviews. The Tier I preliminary support status may be
modified through evaluation of the TSI, water quality related fish kills, and the composition and abundance of
cyanobacteria, also known as harmful algal blooms. The Tier II evaluation could adjust the preliminary
support-status ranking if at least two of the three criteria indicate a different support status.
Tier I Assessment
Drinking Water Use Support
Drinking water use support is assessed through evaluations of pH, toxics, E. coli, and harmful algal blooms
(HABs). Please review the Toxics Parameter Assessments for All Waters, Escherichia Coli Assessment for
All Waters, and Harmful Algal Blooms (HAB) assessment sections for further information regarding drinking
water use assessments for toxics, E. coli, and HABs. The evaluation process of pH is the same as the
requirements for aquatic life uses described below.
Recreational Use Support
Recreational use support is assessed through evaluation of pH, E. coli, and HABs. The pH evaluation is the
same as the requirements for aquatic life uses described below. Please review the Escherichia Coli
Assessment for All Waters and HAB assessment sections for further information regarding recreational use
assessments for E. coli and HABs.
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Aquatic Life Use Support
Lake monitoring routinely involves collecting pH, temperature, and DO measurements at approximately one-
meter intervals throughout the water column from the surface to the lake bottom. (Note: the measurement
interval may be modified in the field depending on waterbody depth). These water column measurements are
compared against Utah water quality standards to assess beneficial use support (Figure 9). A separate
process is used to determine whether sufficient habitat is available for aquatic life for waterbodies that are
thermally stratified (Figure 10).
Agricultural Use Support
Agricultural use support is assessed through evaluations of TDS and toxic parameters. For further information regarding agricultural use assessments, please review the Total Dissolved Solids: Agricultural Use Support section for TDS and Toxic Parameter Assessments for All Waters section for toxic parameters.

pH, All Lakes and Reservoirs
Beneficial Use Supported
The beneficial use is supported if the number of exceedances is less than or equal to 10% of the
measurements (see Figure 10, Panel A).
No
Figure 9. Process using conventional (nontoxic) parameters to assess lakes that are mixed.
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Beneficial Use Not Supported
The beneficial use is not supported if greater than 10% of the measurements (minimum of two discrete
measures outside thresholds) exceed the pH criterion (Figure 21, Panel B).

Temperature and Dissolved Oxygen: Mixed Lakes and Reservoirs
Temperature
The criteria used to assess the beneficial use support are based on profile data. If the temperature criterion is
exceeded in more than 10% of the measurements, with a minimum of two discrete measures exceeding
criteria from any individual sampling event, the site is considered to be not supporting of aquatic life uses.
Beneficial Use Fully Supported
The beneficial use is supported if the number of exceedances is less than or equal to 10% of the
measurements (see Figure 11, Panel A).
Figure 10. Plots of pH measurements (blue dots) against lake depth for a waterbody meeting (Panel A) and exceed (Panel B) the pH water quality standards.
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The beneficial use is not supported if more than 10% of the measurements exceed the temperature standard
(see Figure 11, Panel B).
Figure 11. Plots of temperature measurements (blue dots) against lake depth for two sites to provide an example of
assessment procedures. Note: The red line illustrates a temperature criterion of 20 degrees Celsius: Class 3A beneficial use.
Dissolved Oxygen
The DO assessment uses data gathered from profiles. The DO assessment uses the minimum criteria of 4.0
mg/L for Class 3A waters and 3.0 mg/L for Class 3B, and 3C waters (UAC R317-2-14, Table 2.14.2). State
standards account for anoxic or low DO conditions that may exist in the bottoms of deep waterbodies (UAC
R317-2-14). For that reason, DO assessments for stratified lakes and reservoirs follow the stratified lakes and
reservoirs assessment methods below.
Beneficial Use Supported
The beneficial use is supported if at least 90% of the oxygen measurements are greater than the standard.
Beneficial Use Not Supported
The beneficial use is not supported if greater than 10% of the oxygen measurements are below the DO standard during any single sampling event.
Temperature and Dissolved Oxygen: Stratified Lakes and Reservoirs
When sample locations demonstrate stratification, a separate assessment technique for temperature and DO
is used to ensure that sufficient habitat for aquatic life exists. Habitat is considered sufficient if at least three
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continuous meters of the water column are meeting the criteria for both temperature and DO. The rationale for
a conclusion of beneficial use support based on the existence of adequate habitat follows the decision
diagram (Figure 12). Figure 13 provides an example of supporting and not supporting beneficial uses based
on the DO and temperature data above the thermocline.

Beneficial Use Supported
The beneficial use is supported if there is sufficient habitat, defined as three continuous meters of the water
column meeting the criteria for both temperature and DO.
Beneficial Use Not Supported
The beneficial use is not supported if there is insufficient habitat for aquatic life based on the DO and
temperature profile.
Figure 12. Beneficial use support based on the existence of adequate habitat.
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Figure 13. Concept of the habitable zone where both DO and temperature are suitable for aquatic life. The site depicted on the top (Panel A) would be considered supporting because the lens where both temperature and DO provide sufficient habitat is greater than three continuous meters (>=3 m). Conversely, the site on the bottom (Panel B) is not supporting aquatic life uses because although there are regions in the water column where dissolved oxygen and temperature criteria are met separately, the region of overlap in the water column for both temperature and dissolved oxygen criteria (approximately 8 meters depth) is less than three meters.
Total Dissolved Solids: Agricultural Use Support
The following rules are used to determine whether a lake is supporting its agricultural beneficial use (Figure
14):
Beneficial Use Supported
The beneficial use is supported if the standard is exceeded in 10% or fewer of TDS samples.
Beneficial Use Not Supported
The beneficial use is not supported if the TDS standard is exceeded in more than 10% of TDS samples.
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Figure 14. Assessment process to determine support of the agricultural beneficial use with TDS data.
Tier II Assessment
Weight of Evidence Criteria
The weight of evidence criteria allows DWQ to use key lines of evidence for assessing a waterbody’s
beneficial use support, including evaluations of Utah’s narrative standard.
The weight of evidence evaluation consists of three components:
• Increasing trophic state index (TSI) trend over the long term (approximately 10 years) or a TSI-Chl-a
greater than 50 (see Carlson’s Trophic State Index section below for more information)
• The observation of water quality based fish kills (see the Narrative Standards for All Waters for more
information) or winter DO measures not meeting the criterion when measured
• Evaluation of phytoplankton community
.
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Figure 15. Tier II assessment process for lakes, reservoirs, and ponds.
Carlson’s Trophic State Index
The Carlson's TSI is calculated using Secchi disk transparency, total phosphorus, and chlorophyll a. TSI
value ranges from 0 to about 100, with increasing values indicating a more eutrophic condition. TSIs are
calculated independently for each indicator (i.e., Secchi disk, chlorophyll a, and total phosphorus) and are not
averaged. Chlorophyll a (TSI-Chl-a) is generally considered the most reliable indicator of trophic status,
followed by Secchi disk (TSI-SDD), and total phosphorus (TSI-TP) (Carlson, 1977).
Carlson's TSI estimate for chlorophyll a is calculated using the following equation:
Trophic status based on Chlorophyll a (TSI-Chl-a): TSI-Chl-a = 9.81 ln (Chl-a) + 30.60, where Chl-a = chlorophyll a concentrations in μg/L.
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Phytoplankton Community
DWQ routinely collects phytoplankton to evaluate the composition and relative abundance of algae and
cyanobacteria. These data are used to identify waterbodies potentially undergoing cultural eutrophication that
may negatively impact beneficial uses. Phytoplankton data are used in the Tier II assessment process
because they may reflect nutrient availability and nutrient ratios. The observation that a waterbody has a
diverse assemblage of diatoms or green algae relative to cyanobacteria or other potentially harmful taxa is
used as a line of evidence that the waterbody is supporting its designated uses. In contrast, a phytoplankton
assemblage dominated by cyanobacteria may be indicative of eutrophication, an increased potential for
harmful algal blooms, and a loss of aquatic biodiversity.
Great Salt Lake
The Great Salt Lake (GSL) is assigned its own beneficial use class (Class 5) and is further divided into five
subclasses (5A–5E) that represent the four main bays (Gilbert, Gunnison, Bear River, and Farmington) and
transitional waters (UAC R317-2-6). The only numeric water quality criterion currently applicable to GSL is a
selenium bird-egg tissue criterion for Gilbert Bay (Class 5A). The beneficial uses of GSL are protected and
assessed by Utah’s narrative water quality standard (UAC R317-2-7.2) in addition to this criterion. The Great
Salt Lake Water Quality Strategy outlines the process for monitoring and criteria development for GSL.
Gilbert Bay Bird-Egg Tissue Assessment
Bird eggs are collected during the nesting season from representative locations within the Gilbert Bay AU or
adjacent transitional wetlands (UAC R317-2-6.5). Selenium concentrations from eggs collected each year are
assessed against the criterion in UAC R317-2-14. Gilbert Bay’s beneficial use will be identified as impaired if
the geometric mean of selenium concentrations from five or more eggs collected in any year exceeds the 12.5
mg/kg criterion. If the geometric mean of selenium concentrations from five or more eggs collected in any
year exceeds 9.8 mg/kg dry weight, DWQ will identify Gilbert Bay’s beneficial use as threatened and initiate
preliminary TMDL studies to evaluate selenium loading sources. If Gilbert Bay is identified as impaired for
selenium, five consecutive nesting seasons meeting selenium criteria will be considered sufficient for delisting
the impairment.
The Gilbert Bay selenium criterion also includes thresholds below 9.8 mg/kg that trigger management actions
(Table 15). DWQ evaluates egg concentrations against these thresholds to inform management decisions,
but these thresholds are not used for use attainment determinations in the IR.
Eggs are also collected as part of discharge monitoring programs for certain dischargers to GSL. Eggs
collected as a part of these programs are specifically intended to characterize discharge outfall conditions and
are therefore not relevant to assessing more general GSL conditions. Eggs collected under these programs
are only used for evaluating discharge permits and are not used in 303(d) assessment of the GSL AUs.

Table 15. Selenium trigger levels and DWQ responses (UAC R317-2-14.2(14)).
Se concentration (mg/kg dry weight) DWQ Response
< 5.0 Routine monitoring with sufficient intensity to determine if selenium concentrations within the Great Salt Lake ecosystem are increasing
5.0 Increased monitoring to address data gaps, loadings, and areas of uncertainty identified
from Great Salt Lake selenium studies
6.4 Initiation of a Level II Antidegradation Review (ADR) by the State for all discharge permit renewals or new discharge permits to Great Salt Lake. The Level II ADR may include an analysis of loading reductions.
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Se concentration (mg/kg dry weight) DWQ Response
9.8 Aquatic life use declared as threatened. Initiate preliminary TMDL studies to evaluate selenium loading sources. 12.5 Aquatic life use declared as impaired. Formalize and implement TMDL.

Toxic Parameter Assessments for All Waters
DWQ identifies toxics as all parameters within UAC R317-2-14 that are not defined as conventional
parameters (see Table 11 and the Lakes, Reservoirs, and Ponds Assessment section).
Data are compared against one or more toxic criteria, depending on the beneficial use, to ensure protection of
designated beneficial uses. One daily measurement at each monitoring location is compared to the chronic
and/or acute criteria for 303(d) assessment purposes. DWQ targets dissolved metals sample collection in
lakes at one meter above the bottom of the deepest site of the waterbody, as this location is the most likely to
identify dissolved metal exceedances in a lake. Dissolved metals are also assessed through this method
when additional metals data are available for other lake locations or depths. The acute and chronic averaging
periods defined in UAC R317-2-14 are not currently applied for 303(d) assessment analysis because
monitoring and sampling frequencies are different and more widely spaced than the acute and chronic
periods typically defined in this rule.
Equation-Based Toxic Parameters
A number of toxic criteria are specified as equations rather than specific values (see footnotes in UAC R317-
2-14). The equations include variables of other chemical constituents or water properties that either reduce or
magnify the extent to which a toxic is harmful to aquatic life. In order to properly apply the correction factor
equations, DWQ uses measured data for the variables in the equation to calculate the appropriate numeric
criteria for the sample. In order to calculate the correct criterion for a pollutant-result value, the monitoring
location site and date of sample must match for the pollutant of concern and the additional parameter(s) that
are needed to complete the equation. In the case where there are missing supplemental data values to apply
the equation, the following rules will be applied.
• Hardness-dependent toxics: For hardness-dependent criteria where a calcium (Ca) or magnesium (Mg)
value is missing and the hardness cannot be calculated, a hardness value reported from the laboratory will
be used. Data without a hardness value are removed from assessments.

• Aluminum, chronic only: If either a field pH or calculated or laboratory hardness is missing, the
aluminum acute default value of 750 microgram per liter (μg/L) provided in Table 2.14.2 of UAC R317-2
will be applied. Otherwise, the following pH and hardness combination and numeric criteria are
applied:
a. pH ≥ 7.0 and (calculated or laboratory reported) hardness ≥ 50 parts per million (ppm): 750 μg/L b. pH < 7.0 and (calculated or laboratory reported) hardness ≥ 50 ppm: 87 μg/L c. pH ≥ 7.0 and (calculated or laboratory reported) hardness < 50 ppm: 87 μg/L
d. pH < 7.0 and (calculated or laboratory reported) hardness < 50 ppm: 87 μg/L

• Ammonia, chronic: DWQ assumes fish early life stages are present at all monitoring locations. The
following equation is used: ((0.0577/(1+10^(7.688-pH))) + (2.487/(1+ 10^(pH-7.688)))) * MIN (2.85,
1.45*10^(0.028*(25-T))).Where (1.45*10^(0.028*(25-T))) is ≤ 2.85, (1.45*10^(0.028*(25-T))) is applied
and if (1.45*100.028*(25-T)) is > 2.85, 2.85 is applied. However, if a field pH or temperature reading is
57
unavailable, a correction factor cannot be made and the result value for ammonia will be removed from
the assessment.
• Ammonia, acute: If a field pH is missing, a correction factor cannot be made, and the result value for
ammonia will be removed from the assessment.
Assessment Process
Once chronic and acute criteria are calculated, toxicant sampling results, where applicable, are compared to
the criteria to determine if the monitoring location is supporting beneficial uses or is impaired due to
exceedances of the standard. Sites with sufficient data (four or more samples) with two or more exceedances
of the acute and/or chronic criteria will result in non-support of the beneficial use. Four or more samples will
be required with one or zero samples exceeding acute or chronic criteria for sites to meet beneficial uses. In
cases where there are fewer than four samples, and one or zero samples are exceeding the acute or chronic
criteria, sites will be placed in Category 3, insufficient data (Figure 16).

Figure 16. Overview of the assessment process for toxic parameters.
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Data Preparation
Following a credible data review and additional QA/QC checks as outlined in DWQ’s Quality Assurance
Program Plan for Environmental Data Operations (DWQ, 2014), DWQ compiles all credible data within the
period of record of concern and makes several adjustments based on the reported limits and sampling
frequencies necessary to conduct the assessment. Similar to the other QA/QC and assessment procedures
outlined in this document, the raw data and accompanying metadata values in Escherichia coli (E. coli)
datasets are not altered. Instead, DWQ uses a series of database comments and flags.
Recreation Season
To ensure protection of recreation uses, E. coli assessments will be conducted on data collected during the
recreation season from May 1 through October 31. The recreation season may be adjusted to be either longer
or shorter based on site-specific conditions. Any site-specific adjustments made to the recreation season will
be documented.
Escherichia coli Collection Events and Replicate Samples
Datasets at a single monitoring location may contain replicate samples or multiple samples collected in the
same day due to sampling design. Single daily values or collection events are required for E. coli
assessments. DWQ defines a collection event as one of the following:
• The daily most probable number (MPN) result value
• A geometric mean of replicates where multiple samples are collected on the same day
• The daily MPN as a quantified value reported as being obtained from a dilution
In cases where replicate samples were taken and there is 1) a quantified MPN value reported from a dilution
and 2) the MPN value reported is greater-than-detect (>2,419.6), the quantified MPN value will be used as the
collection event for assessment purposes. In this scenario, MPNs reported as greater-than-detect are not
used to calculate the geometric mean for the collection event.
Data Substitution for Calculating the Geometric Mean
Assessments use the geometric mean of representative samples to determine if E. coli standards are met. E.
coli data that are reported as less- than-detect (< 1) or 0 will be treated as a value of 1 to allow for the
calculation of a geometric mean. Similarly, E. coli data that are reported as greater-than-detect (> 2,419.6) will
be treated as 2,420 to allow for the calculation of the geometric mean.
Use Designation
DWQ assesses use support for each monitoring location once the data are compiled. All waters of the state
are classified for contact recreation (Class 2), and some waters are classified as drinking water sources
(Class 1C). These uses have specific associated E. coli standards that are used to determine use support.
The numeric criteria within UAC R317-2-14 are applied to Class 2 and Class 1C uses based on the beneficial
use assignments to a waterbody or segment within a waterbody.
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Assessment Process
Annual Recreation Season Assessment
DWQ begins the assessment process by gathering information on health advisories and/or closures issued
during the recreation season. If a waterbody had two or more E. coli–related beach closures and/or health
advisories in a recreation season, or if a health advisory and/or closure was issued for recreational access to
a waterbody for two or more weeks, the waterbody is considered impaired and no further assessment is
conducted (Figure 17). If there were fewer than two closures or advisories, or if the closure lasted less than
two weeks, the assessment process continues using E. coli concentrations.

Figure 17. Considering E. coli-related beach closures and/or health advisories.
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To ensure protection of recreation and drinking water uses of assessed waterbodies of the state, DWQ
considers three scenarios based on sampling frequency and the number of collection events at a monitoring
location:
• Scenario A: A seasonal assessment against the maximum criterion (Figure 18)
• Scenario B: A 30-day geometric mean assessment (Figure 19)
• Scenario C: A seasonal geometric mean assessment (Figure 20)
Scenario A
If there are greater than or equal to five collection events spaced 48 hours or more apart within a recreation
season, then all collection events within the recreation season are used to make an assessment (see Figure
18).
• DWQ does not make impairment decisions based on one exceedance. If the monitoring location has less
than 10 collection events within a recreation season, then one collection event may exceed the numeric
criterion and the site will still be considered in Scenarios B and C. If two or more collection events exceed
the numeric criterion, then the monitoring location is not supporting the beneficial use, and the next
beneficial use is assessed.
• If there are 10 or more collection events within a recreation season, a percent exceedance is calculated
by dividing the number of collection events that exceed the maximum criterion by the total number of
collection events. If the calculated percentage is 10% or less, the monitoring location is then assessed
using Scenarios B and C. If the calculated percentage is greater than 10%, the monitoring location is not
supporting its beneficial use, and the next beneficial use is assessed.
• If there are less than five collection events spaced 48 hours or more apart within a recreation season
then the monitoring location is placed in the insufficient data category.
• If one or more collection events exceed the maximum criterion, then the monitoring location is placed in
the insufficient data with exceedances category.
• If no collection events exceed the maximum criterion, then the monitoring location is placed in the
insufficient data, no exceedances category.
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Figure 18. Scenario A: A seasonal assessment using the maximum criterion at a monitoring location.
Scenario B
If the site’s calculated percent exceedance of the maximum criterion is less than or equal to 10% or no more
than 1 sample exceeding the maximum criterion in the case of a dataset with 5 to 9 samples, the site is
then assessed using the 30-day geometric mean criterion (see Figure 19). There must be a minimum of
five collection events in 30 days with at least 48 hours between collection events in order to assess against
the 30-day geometric mean criterion directly. This ensures that collection events are adequately spaced and
are representative of ambient conditions.
Step 1: Determine if there are ≥5 collection events within a 30-day period.
• Count the number of collection events collected between each sample date (day 1) and the sample date
plus 29 days (day 30).
Step 2: Determine if the collection events are representative (must have ≥5 collection events within a 30-day
period).
• Count the number of collection events collected between each sample day (day 0) and the sample date
plus 2 days (day 3).
• If there are two collection events within this period, only one sample will be considered representative.
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Step 3: Calculate the 30-day geometric mean.
• If there are ≥5 representative samples in a 30-day period, then all collection events will be used to
calculate the 30-day geometric mean.
• If ≥1 30-day geometric mean exceeds the 30-day criteria, the site is not supporting beneficial uses. If
there are not representative data for Scenario B, or if the 30-day geometric mean did not exceed the 30
day criteria, the site is assessed using Scenario C.

Scenario C
Figure 19. Scenario B: An assessment using the 30-day geometric mean for monitoring locations with five or more collection events within 30 days.
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If adequate (at least five samples) and/or representative data spaced by at least 48 hours are not available to
assess against the 30-day geometric mean, DWQ will assess E. coli data for the recreation season, provided
there are at least five collection events during the defined recreational season. Exceedances of the geometric
mean criterion will result in the site being classified either as impaired (minimum of 10 collection events in a
recreation season) or as insufficient data (sample size is more than five but fewer than 10) (see Figure 20).

Figure 20. Scenario C: A seasonal geometric mean assessment.
Summarizing Assessment Results
When determining beneficial use support of a monitoring location with assessment results across multiple
years, the following rules are applied, in the following order:
Not Supporting (Category 5)
• A waterbody has two or more posted health advisories or beach closures during any recreation season.
• Any monitoring location with five to nine collection events and two or more collection events that exceed
the maximum criterion.
• Any monitoring location where the calculated percent exceedance of the maximum criterion within a
recreation season for E. coli concentrations is greater than 10% for 10 or more collection events.
• Any monitoring location where the 30-day geometric mean exceeds the 30-day geometric mean criterion
(minimum five collection events with at least 48 hours between collection events).
• Any monitoring location where the recreational season geometric mean exceeds the 30-day geometric
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mean criterion (minimum of 10 collection events).

Insufficient Data
• Sites with nine or fewer samples that could not be fully assessed in Scenarios A, B, or C will be listed as
insufficient data, provided impairment is not suggested by posted health advisories or beach closures.
Combinations of Category 3 (with no exceedances), 2, and/or 1
• If there is no evidence of impairment at a site by any of the assessment approaches over the period of
record, the assessment analysis from the most recent year outweighs the results from previous years.
DWQ’s process for merging assessment results from multiple locations within an AU is discussed in
more detail in Determinations of Impairment: All Assessment Units.
Supporting (Category 1 or 2)
• No evidence of impairment by any assessment approach for all recreation seasons over period of record.
A fully supporting determination can be made with a minimum of five collection events during the
recreational season.
Combining E. coli with Other Parameter Assessment Results
Until the determination of impairment and the review of additional supporting information are completed by
reviewers, parameter assessments at an individual monitoring location and results from multiple monitoring
locations within the same AU are not summarized and combined (see Determinations of Impairment for more
details).

Pollution Indicator Assessments for All Waters
Several parameters and beneficial uses in UAC R317-2 are identified as pollution indicators and have
footnotes indicating that further investigations should be conducted when levels are exceeded. To capture this
footnote in the assessment process, DWQ reviews preliminary pollution indicator assessments during the
Secondary Review process to determine whether pollution indicators demonstrate clear and convincing
evidence of supporting or not supporting the beneficial uses assigned to the waterbody in UAC R317-2.
Secondary reviews incorporate pollution indicator data into assessment-category determinations and rely on
multiple lines of evidence, including pollution indicator thresholds, the presence or absence of other indicator-
associated water quality issues, potential pollutant sources, and other site- or watershed-specific knowledge,
to determine whether listing or delisting on a pollution indicator parameter is appropriate or whether to
prioritize waterbodies for additional monitoring.

Narrative Standards for All Waters
Utah’s water quality standards contain narrative criteria that protect beneficial uses in addition to the numeric
criteria used to perform water quality assessments. The narrative criteria state:
It shall be unlawful, and a violation of these rules, for any person to discharge or place any waste or other
substance in such a way as will be or may become offensive such as unnatural deposits, floating debris, oil, scum, or other nuisances such as color, odor to taste; or cause conditions which produce undesirable aquatic
life or which produce objectionable tastes in edible aquatic organisms; or result in concentration or
65
combinations of substance which produce undesirable physiological responses in desirable resident fish, or other desirable aquatic life, or undesirable human health effect, as determined by bioassay or other tests
performed in accordance with standard procedures; or determined by biological assessments in (UAC) Subsection R317-2-7.3.
DWQ will apply the narrative criteria to protect human health and aquatic life where evidence exists that
human-caused actions have produced any of these undesirable outcomes in a waterbody. Narrative
standards may be used to make an impairment determination for drinking-water closures, fish kills, harmful
algal blooms (HABs), beach closures for swimming, and health advisories for the consumption of fish.
Assessment of E. coli data and associated beach closures to protect human health provide an additional
weight of evidence for defining the impairment of recreational uses and is addressed in more detail earlier in
this document in the Escherichia Coli Assessment for All Waters section.
DWQ will assess a site as impaired for 1C uses if the Utah Division of Drinking Water or a local municipality
issues an advisory or closure for a surface drinking water source, unless data show that the problem has
been resolved.
Fish Kills
DWQ requests information on reported fish kills from the Utah Division of Wildlife Resources and other
stakeholders. These data are used with water quality data to make final assessment decisions. For example,
sites that would generally not be assessed due to small sample sizes may be listed as impaired if fish kills
have also been observed in the waterbody.

Harmful Algal Blooms (HAB)
In fresh waters, HABs are typically composed of cyanobacteria; a phylum of photosynthetic bacteria sometimes called
blue-green algae. Recreational exposure to HABs can result in negative human health and aquatic life impacts (EPA 2019). DWQ‘s HAB assessment methods apply to non-benthic HABs occurring in waterbodies with frequent primary contact recreational uses, including those currently designated with 2A uses and those where existing frequent primary contact recreational uses have been documented. Potential impacts of HABs on aquatic life uses are currently
addressed through eutrophication-related aspects of general lakes, reservoirs, ponds, flowing surface waters or the State, and canal assessment methods (e.g. dissolved oxygen, pH, and lake Tier II assessments).
DWQ‘s HAB assessment methods use two independent indicators to determine beneficial use support: cyanotoxin concentrations and waterbody access or use limitations. DWQ collects samples during HAB events for use in recreational use assessments using DWQ‘s HAB Standard Operating Procedures (SOP, DWQ 2022). DWQ‘s assessment methods rely on EPA‘s recommended criteria for microcystin and cylindrospermopsin (EPA 2019). Thresholds for additional cyanotoxins may continue to be added to the assessment methods as they become available.
To ensure protection of recreation uses, HAB assessments will be conducted on data collected during the recreation season
from May 1 through October 31. The recreation season may be adjusted to be either longer or shorter based on site-specific conditions. Any site-specific adjustments made to the recreation season will be documented.
Table 16. Cyanotoxin thresholds for recreational use assessments based on EPA (2019) guidance.
Microcystins magnitude (ug/L) Cylindrospermopsin magnitude (ug/L) Duration Frequency
8 15 1 in 10-day assessment period across a recreational season
Not more than 3 excursions* in a
recreational season in more than one year over the period of record
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* An excursion is defined as a 10-day assessment period with any toxin concentration higher than the recommended criteria magnitude. When more than three excursions occur within a recreational season and that pattern reoccurs in more than one year over the IR period of record, it is an indication the water quality has been or is becoming degraded and is not supporting its recreational use.
Beneficial Use Supported
The beneficial use is fully supported if, over the period of record: Cyanotoxin concentrations have not been identified above recreational use thresholds (Table 16), AND a Warning Advisory, Danger Advisory, or closure has not been issued for recreational access to a waterbody.
Beneficial Use Not Supported
The beneficial use is not supported if, in representative samples for recreational uses, in two or more years in the period of record: Cyanotoxin concentrations above recreational guidelines (Table 16) have been reported in more than three 10-day assessment periods in a recreational season, OR a Warning Advisory, Danger Advisory, or closure has been issued for recreational access to a waterbody for two or more 2-week periods in a recreational
season.
Insufficient Data and Information with Exceedances (IR Category 3)
The waterbody will be placed in the insufficient data category if: It does not meet either of the Beneficial Use
Supported or Beneficial Use Not Supported criteria (above), but cyanotoxin concentrations exceeded recreational use thresholds (Table 16) in three or fewer 10-day assessment periods in a recreation season, OR a Warning
Advisory, Danger Advisory, or closure has been issued for recreational use for less than two 2-week periods. These waterbodies will be prioritized for further sampling and evaluation.
Fish Tissue Assessments and Consumption Health Advisories
DWQ has collected fish tissue samples for mercury analysis in waterbodies throughout the state since 2000.
Consumption advisories have been issued based on the EPA-published ambient water quality criterion for
methylmercury for the protection of people who eat fish and shellfish. This criterion is 0.3 milligram (mg) methylmercury
per kilogram (kg) fish tissue wet weight. If all fish (small and large) of the same species at a monitoring location have a
mean mercury concentration of > 0.3 mg/kg, additional statistical tests are used to determine if a consumption advisory is
necessary. If the mean is < 0.3 mg/kg, no advisory is issued. In several instances, size class advisories have been
issued when it is apparent that only the larger size class exceeds the safe consumption criterion.
Using a t-test, the p-value is considered for locations with a mean mercury concentration of > 0.3 mg/kg. In
hypothesis testing, a p-value is the statistical probability (over repeated measures) that the mean value (or
more extreme value) is observed given that the null hypothesis is true. In the case of health advisories,
DWQ uses a t-test to evaluate the difference between a mean mercury concentration > 0.3 mg/kg and the
expected mercury value of 0.3 mg/kg. In this statistical test, a smaller p-value indicates a lower probability
the statistical comparison supports the null hypothesis that mercury concentrations are at an acceptable
level. DWQ uses a p-value of 0.05 as a threshold for consumption health advisories. If a species has a mean
of > 0.3 mg/kg and a p-value < 0.05, a consumption advisory is issued. If a species has a mean of > 0.3
mg/kg but a p-value of > 0.05, an advisory is not issued. The consumption advisories are based on long-term
consumption; therefore, the mean is the most appropriate and commonly used parameter to estimate
exposure.
In an effort to control for false negatives, DWQ calculates 95% confidence limits of the mean mercury
concentration. If the upper confidence limit is above 0.3 mg/kg, that site is targeted for additional sampling.
When an advisory is warranted, DWQ sends the data to the Utah Department of Health toxicologist, who uses
the mean mercury concentration to calculate the actual consumption recommendations. Those calculations
are based on the following:
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• Average adult weight: 70 kg (154 pounds). Average adult meal size: 227 grams (8 ounces)/meal
• Average child weight: 16 kg (35 pounds). Average child meal size: 113 grams (4 ounces)/mealConsumption amounts are calculated for three target populations: pregnant women and children < 6 years old; women of child-bearing age and children between 6–16 years old; and adult women past child-bearing age and men >16 years old.
Mercury Assessment Process
The current approach for mercury assessments for aquatic life is different than the consumption advisory
process. The assessment is based on the U.S. Food and Drug Administration (FDA) recommended value of
1.0 mg/kg. The FDA set the consumption concentration at 1.0 mg/kg, which correlates to the water column
mercury concentration of 0.012 µg/L identified in previous studies by EPA (EPA, 1985). Utah’s water quality
standard for mercury is 0.012 µg/L as a four-day average. Therefore, the corresponding fish tissue
concentration of 1.0 mg/kg is used for assessment.
Beneficial Use Supported (Category 1)
• No fish consumption advisories for mercury are in place.
• Mean fish tissue mercury concentration for all individuals of the same species at a location is less than
0.3 mg/kg and p-value is < 0.5.
Insufficient Data with Exceedances (Category 3)
• Fish consumption advisories for mercury are in place, but the mean fish tissue mercury concentration for
all individuals of the same species at a location is less than or equal to 1.0 mg/kg.
Beneficial Use Not Supported (Category 5)
• Fish consumption advisory for mercury is in place.
• Mean fish tissue mercury concentration is greater than 1.0 mg/kg.
For additional information and the most up-to-date list of consumption advisories, please visit
fishadvisories.utah.gov.
Determinations of Impairment: All Assessment
Units
Each use and parameter within a waterbody is assigned a provisional EPA-derived assessment category after
the initial assessment of credible data against the numeric criteria in UAC R317-2. To verify the use and
parameter-specific assessment results and consolidate the often multiple parameter assessments into one
result per waterbody, DWQ must consider the quantity of data and the extent to which such data demonstrate
clear and convincing evidence of supporting or not supporting the beneficial uses assigned to the waterbody
DWQ considers the following information to determine whether a waterbody is supporting or not supporting its
beneficial uses:
• Individual assessment of water quality standards at a single site
• Independent applicability
• Multiple lines of evidence and several levels of secondary reviews
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Individual Assessment of Water Quality Standards
DWQ first considers the individual use and parameter-specific assessment results from the monitoring-
location level data to determine whether a waterbody is supporting or not supporting the beneficial uses
assigned in UAC R317-2. Each use and parameter assessed for the waterbody is assigned a provisional
EPA-derived assessment category. Unless noted in the waterbody-specific data assessment protocols, the
assessment policies outlined in this document provide a direct and quantifiable method and documentation of
data supporting or not supporting DWQ’s water quality standards versus data and information that are
developed using surrogate parameters or indicators. Because individual assessments at a single monitoring
location site offer a more direct measure of supporting or not supporting water quality standards in UAC
R317-2, DWQ places a greater weight on individual assessment decisions that follow the data assessment
protocols in this document.
DWQ looks across the multiple parameter-specific assessment results that exist for a location and
consolidates the results into a preliminary assessment at the individual site level after review of the individual
water quality standard assessments for a beneficial use. DWQ then assigns one EPA-derived assessment
decision category as defined in Table 1 to each monitoring location.
Conflicting Assessments of Water Quality Standards
DWQ applies the policy of independent applicability to address the possibility of conflicting results among
different types of data (e.g., biological versus conventional pollutant, toxics versus E.coli) at the site and AU
level and goes through a series of considerations to determine if discrepancies are due to
• Differences in data quality
• Environmental factors such as the application of the water-effects ratio, development of site-specific
criteria, revision to numeric criteria in UAC R317-2, or completion of a use attainability analysis
Sites with conflicting assessment results may be listed as Category 3 (insufficient data and information). This
allows DWQ to examine conflicting lines of evidence when concerns about the quality of independent
datasets cannot be resolved through evaluation and documentation of the QA/QC issues that led to
acceptance of one dataset and the resulting assessment result. Specific assumptions regarding model
applicability applied during the biological assessment process are discussed in the Biological Assessment
section. Similarly, if the application of water-effects ratio, justifiable site-specific criteria change, or change in
beneficial uses based on a use attainability analysis cannot rectify the difference in the assessment results,
then a Category 3 may be warranted. All evaluations of conflicting assessment decisions will be made in
consultation with EPA on a case-by-case basis.
Aggregation of Site-Specific Assessments to Assessment Unit Categories
For reporting purposes, DWQ aggregates all site-specific water quality assessments within an AU to a single assessment category for that AU as described in Table 1. A flowchart describing this process is presented in Figure 21 (see Appendix 3 for additional detail).
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Figure 21. Process of assigning EPA categories to AUs based on results of monitoring location assessments.
Secondary Review
DWQ conducts a secondary review of listing determinations after consolidation of all individual assessment
results and assignment of preliminary assessment category(s) for an AU, The secondary review process
allows DWQ to apply site/waterbody-specific knowledge and additional data quality controls to evaluate the
extent to which data used in the preliminary assessment demonstrate clear and convincing evidence of
supporting or not supporting the beneficial uses assigned to the waterbody in UAC R317-2 DWQ
recognizes that input from reviewers during public comment periods, in addition to the internal secondary
review process, may provide key information on the data used in listing decisions. To ensure consistency in
its use among different professionals, the secondary review process will be applied in a select number of
scenarios using a standard set of evaluation guidelines (Appendix 2).
If documentation from the secondary review provides sufficient evidence to modify the basis and result of the
preliminary assessment, the preliminary assessment decision based on the data assessment procedures
outlined in this document will be overwritten. For example, preliminary listings for Category 5, Category 1, or
Category 2 waters could be re-assigned as Category 3, insufficient data and information, based on one or
more factors outlined in Appendix 2. DWQ will document the original category assignment and a justification
for the secondary review to ensure tracking and transparency.
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Assessment Unit Re-segmentation
DWQ may decide it is appropriate to re-segment (i.e. “split”) an existing AU polygon into two or more new
AUs rather than aggregate those conflicting assessments into a single AU scale category when site-specific
assessments within a single AU conflict. AUs where water quality criterion exceedances are clearly isolated to
a relatively small, hydrologically distinct portion of the larger AU may be re-segmented to more accurately
reflect that variation in water quality. For example, a large AU with an impairment isolated to a single tributary
may be re-segmented into two AUs: one for the impaired tributary and another for the rest of the existing AU.
Assessment categories for both AUs are then determined following standard aggregation (Figure 21) and
the delisting procedures discussed in the Delistings section). This results in a higher resolution and overall
more accurate assessment. DWQ does not consider it appropriate to re-segment an AU when exceedances
are observed in multiple locations throughout an AU or where impaired sites are not hydrologically distinct
from unimpaired portions of the AU.
If after aggregating all of the assessments into one assessment category for an AU, DWQ determines that the
supporting or not supporting assessment result decision is not representative of the entire AU, DWQ will
investigate further to determine whether the supporting or not supporting decision is widespread or limited to
individual portions of the waterbody, such as specific tributaries or reaches. Results from the analysis will be
categorized as follows:
Entire AU not supporting (Category 5): DWQ will recommend that the AU not be re-segmented and the
entire AU be listed as not supporting. When data from multiple sites or tributaries within an AU indicate
multiple (or a combination of) sites that do not support beneficial uses (Category 5) and insufficient data with
exceedances (Category 3)
Not supporting tributaries listed as not supporting (Category 5): DWQ may recommend the AU be
re-segmented into two AUs and that only the tributaries with data indicating impairment are listed as not
supporting if data from main stem and one or more other tributaries indicate a combination of any of the
following:
• Insufficient Data with Exceedances (Category 3)
• No Evidence of Impairments (Category 2)
• Supporting (Category 1)
• Needs Further Investigations (Category 3)
• Insufficient Data with No Exceedances (Category 3)
• Not Assessed (Category 3)
The rest of the AU will be assigned a category following procedures as outlined in Figure 21.
Identifying Causes of Impairments
DWQ will determine if the impairment or impairments are driven by pollutants, pollution, unknown, or natural
causes once an AU is assigned an EPA assessment category that is representative of conditions in the AU
(see Table 1). DWQ will identify causes of impairment by a pollutant with specific numeric water quality
criteria identified in UAC R317-2-14. Pollution is a generalized term for causes of water quality impairment
that can include multiple pollutants and other factors such as the absence or lack of water, lack of riparian
vegetation, and other modifications that affect a waterbody’s ability to support aquatic habitat and other
designated uses. With the exception of naturally occurring causes, only one cause will be applied to a not-
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supporting waterbody and parameter. Procedures on how DWQ identifies the cause of impairments are
described in the section below. These identified causes of impairments are reported to the EPA through
ATTAINS.
Pollutants
DWQ uses CWA’s definition as a guide to define pollutant-driven impairments (Category 5) as those resulting
from the following:
… dredged spoil, solid waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical
wastes, biological materials, radioactive materials (except those regulated under Atomic Energy Act of 1954, as amended), heat, wrecked or discarded equipment, rock, sand, cellar dirt, and industrial, municipal, and
agricultural waste discharged into water. (UAC R317-1)
DWQ also includes certain radiological constituents that are regulated under the state’s Water Quality Control
Act.
For the purpose of the 303(d) list, causes for impairments due to toxic parameters will be identified as the
parameter for which there is an impairment. In the case of conventional parameters such as DO, temperature,
pH, and biological scores, the cause will be assigned as the parameter that was assessed until a TMDL or
pollution prevention plan identifies an alternative cause of the impairment.
DWQ will list the waterbody and the not-supporting parameter(s) as impaired for that pollutant (cadmium, iron,
etc.) when an impairment for a waterbody or segment within a waterbody is identified as pollutant-driven.
Waterbodies that are not supporting their beneficial uses due to pollutant impairments require future
development of a TMDL or application of a TMDL alternative (Advanced Restoration Plan).
Where DWQ can identify that an impairment was not driven by a pollutant, it may consider whether the not-
supporting assessment was driven solely by pollution versus a pollutant or by an unknown cause. DWQ will
use CWA’s definition of pollution as a guide when determining if an impairment resulted from “the man-made
or man-induced alteration of the chemical, physical, biological, and radiological integrity of water.”
Waterbodies with not-supporting parameters that are driven solely by pollution problems do not require the
future development of a TMDL and are candidates for a non-pollutant impairment (4C) assessment category.
Details on DWQ’s process for using EPA’s 4C assessment category are described in section Category 4C.
Unknown Sources
For the purpose of the IR, sources of pollution contributing to an impairment will be reported in the 303(d) list
to EPA as “unknown” until a TMDL or special study identifies the sources and any additional causes of
impairment.
Natural Conditions
DWQ will retain the not-supporting assessment decision in cases where it or a stakeholder can demonstrate
that the natural conditions of the waterbody or segment within a waterbody are the key factors for an
impairment(s). However, DWQ’s response to such exceedances differs unless a site-specific standard has
been promulgated. Site-specific standards require documentation that demonstrates the extent to which the
violations were due to natural conditions. Proposed changes to standards will be developed once this
documentation is assembled Please review DWQ’s Standards webpage for more information on the review
and approval process for developing standards and numeric criteria for exceedances caused by naturally
occurring conditions.
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Revising the 303(d) List and Other Categorical
Assessments
Upon validating the strength and extent of the impairments within a waterbody or segment within a waterbody,
DWQ includes newly proposed and previously listed not supporting (Category 5) waterbodies on the updated
303(d) list unless the waterbody or waterbody segment(s) is currently included in the IR’s TMDL-approved
(Category 4A), pollution control (Category 4B), non-pollutant impairment (Category 4C), or delisting lists.
Details on how and when DWQ will not apply or carry an impaired listing (not supporting, Category 5) forward
on DWQ’s 303(d) list are described below. Category 4A
DWQ may choose to not list or remove an impaired waterbody or segment within a waterbody on the state’s
303(d) list by calculating the maximum amount of a pollutant that a waterbody can receive while still meeting
the state’s water quality standards. This calculation and analysis work must be formalized in a TMDL and go
through a thorough internal and external review process. This TMDL must be provided to the public for review
and comment, submitted to the Water Quality Board for approval, reviewed by the Legislative Natural
Resources, Agriculture, and Environment Interim Committee if implementation costs exceed $10 million or the
full State Legislature for approval if implementation costs exceed $100 million, and ultimately to EPA for their
approval. Information on DWQ’s process for developing and implementing a TMDL can be found on DWQ’s
Watershed Protection Section website and EPA’s TMDL 303(d) website. Where DWQ has documentation of
a TMDL approved by the Water Quality Board and EPA for an impaired parameter within a not-supporting
waterbody or segment within a waterbody, DWQ will override a current or previous not-supporting Category 5
listing decision at the AU level as follows:
Whole AU Category 4A, TMDL-approved if:
The only impairments within the waterbody or segment within the waterbody are included in the approved
TMDL.
There are additional impairments within the waterbody or segments within the waterbody that are addressed
in a Category 4B demonstration plan (described in section Category 4B and Appendix 4) and are not included
in the approved TMDL. If the parameters included in the approved Category 4B demonstration plan are still
not supporting or are insufficient data with exceedances in the current assessment cycle, DWQ will indicate
that those parameters have an approved Category 4B demonstration plan in place.
There are additional impairments within the waterbody or segments within the waterbody that are pollution-
driven (Category 4C) and not included in the approved TMDL. DWQ will indicate that those parameters are
pollution versus pollutant driven if the pollution-driven parameters are still not supporting or are insufficient
data with exceedances in the current assessment cycle.
Whole AU Category 5, Not Supporting if:
There are any additional pollutant impairments within the waterbody or segments within the waterbody that
are not included in the approved TMDL. DWQ will indicate that those parameters have an approved TMDL in
place if the parameters included in the approved TMDL are still not supporting or are insufficient data with
exceedances in the current assessment cycle.
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Category 4B
DWQ may choose to not list or remove an impaired waterbody or segment within a waterbody on the state’s
303(d) list by developing a plan that ensures, upon implementation, that the waterbody will meet state water
quality standards within a reasonable time period and through state- and EPA-approved pollution-control
mechanisms. Similar to a TMDL, a Category 4B demonstration plan must go through a robust internal and
external review process. Once DWQ or a stakeholder develops a plan for consideration, DWQ will present the
plan to the Water Quality Board and submit the board-approved plan to EPA for final approval. More
information on the Category 4B demonstration plan process can be found in Appendix 4 and in EPA’s
Category 4b – A Regulatory Alternative to TMDLs document.
Where DWQ has documentation of an EPA-approved Category 4B demonstration plan for an impaired
parameter within a not-supporting waterbody or segment within a waterbody, DWQ will override a current (or
previous) not-supporting Category 5 listing decision at the AU level as follows:
Whole AU Category 4A, TMDL-approved if:
There are any additional impairments within the waterbody or segments within the waterbody that are
addressed in an approved TMDL (Category 4A) and are not included in the approved Category 4B
demonstration plan. DWQ will indicate that those parameters have an approved Category 4B demonstration
plan in place if the parameters included in the approved Category 4B demonstration plan are still not
supporting or are insufficient data with exceedances in the current assessment cycle.
Whole AU Category 4B, Pollution Control if:
The only impairments within the waterbody or segment within the waterbody are included in the approved
Category 4B demonstration plan.
There are additional impairments within the waterbody or segments within the waterbody that are pollution
driven (Category 4C) and are not included in the approved Category 4B demonstration plan. DWQ will
indicate that those parameters are pollution rather than pollutant driven if the pollution-driven parameter
impairments are still not supporting or are insufficient data with exceedances in the current assessment cycle.
Whole AU Category 5, Not Supporting if:
There are any additional pollutant impairments within the waterbody or segments within the waterbody that
are not included in the approved Category 4B demonstration plan. DWQ will indicate that those parameters
have an approved Category 4B demonstration plan in place if the parameters included in the approved
Category 4B demonstration plan are still not supporting or are insufficient data with exceedances in the
current assessment cycle.
Category 4C
DWQ may choose to not list or remove an impaired waterbody or segment within a waterbody on the state’s
303(d) List when DWQ can demonstrate that the parameter-specific impairment (or impairments) is driven by
pollution and not by a pollutant or pollutant that causes pollution; for example, an impairment driven by
hydrologic modification or habitat degradation. Unlike a TMDL or Category 4B demonstration plan, the
analysis determines if the cause of impairment is driven by pollution and does not require formal approval
from the Water Quality Board or EPA. The determination is reviewed internally by DWQ and by stakeholders
during the public comment period of the draft IR and 303(d) list.
For the draft IR and 303(d) list, DWQ will temporarily assume “approval” of any pollution-driven analysis work
and supersede a current or previous not supporting Category 5 listing decision at the AU level as follows:
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Whole AU Category 4A, TMDL-approved if:
All impairments within the waterbody or segments within the waterbody are addressed in an approved TMDL
(Category 4A). DWQ will indicate that those parameters are pollution- rather than pollutant-driven for
pollution-driven impairments that are still not supporting or are insufficient data with exceedances in the
current assessment cycle.
Whole AU Category 4B, Pollution Control if:
All impairments within the waterbody or segments within the waterbody are addressed in an approved
Category 4B demonstration plan. DWQ will indicate that those parameters are pollution driven for pollution-
driven impairments that are still not supporting or are insufficient data with exceedances in the current
assessment cycle.
Whole AU Category 4C, Non-Pollutant Impairment if:
The only impairments within the waterbody or segment within the waterbody are included in the approved
Category 4C demonstration plan.
Whole AU Category 5, Not Supporting if:
There are any additional pollutant impairments within the waterbody or segments within the waterbody. DWQ
will indicate that those parameters are pollution-driven for pollution-driven impairments that are still not
supporting or are insufficient data with exceedances in the current assessment cycle.
DWQ will provide stakeholders with draft IR and 303(d) list documentation during the public comment period
to demonstrate why the impaired parameter within the waterbody or segment within the waterbody is
pollution- and not pollutant-driven and will not require the future development of a TMDL.
Delistings
The fourth and final alternative DWQ has at its disposal is to demonstrate good cause to stakeholders and
EPA that a previously impaired parameter and waterbody or segment within a waterbody is now meeting
water quality standards in UAC R317-2. Good cause occurs when DWQ can demonstrate one or more of the
following categories and scenarios:
Meeting water quality criteria due to restoration activities
The waterbody has improved due to implementation of nonpoint source projects and/or revised effluent limits
and post-implementation data indicate that the impairment has been resolved. This assessment may be
based on additional data beyond that which is typically used in assessments, including before–and-after
project implementation monitoring. In some cases, demonstration of improvement may be based on a
different time period for data collection that corresponds with known watershed improvements.
Applicable water quality standard attained due to change in water quality standard
Adoption of revised water quality standards and/or uses so the waterbody now meets the revised standards
and/or uses.
Applicable water quality standard attained due to change in 303(d) assessment methods
Development of a new listing method consistent with the state water quality standards and classifications and
federal listing requirements. This includes all information contained in this document and posted on DWQ’s
Call for Data webpages.
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Meeting water quality criteria with new data
Assessment and interpretation of older data that was not originally included in the previous assessment
and/or more recent or more accurate data that demonstrate that the applicable classified uses and numeric
and narrative standards are being met.
Listed water not in state's jurisdiction
Inappropriate listing of a water that is located within Indian country as defined in 18 United States Code 1151.
Original basis for listing was incorrect
Flaws in the original analysis of data and information that led to the waterbody-pollutant combination being
incorrectly listed. Such flaws may include the following: (1) calculation errors in the data assessment methods
outlined in the 303(d) assessment methods from that assessment cycle; (2) errors produced when reviewing
credible and representative data information; (3) mapping errors generated during the validation of monitoring
location information and assigning AU designations; (4) discrepancies between the beneficial use
assignments in UAC R317-2 and the IR geo-location information files for internal and external data; (5),
incorrect identification and assessment of a waterbody type; and (6) application of the wrong numeric criteria
to a beneficial use.
New modeling
Results of more sophisticated water quality modeling that demonstrate that the applicable classified uses and
numeric and narrative standards are being met.
Effluent limitations
Demonstration pursuant to 40 CFR 130.7(b)(1)(ii) that there are effluent limitations required by state or local
authorities that are more stringent than technology-based effluent limitations required by the CWA and that
these more stringent effluent limitations will result in support of classified uses and numeric and narrative
standards for the pollutant causing the impairment.
Other
There is other relevant information that supports the decision not to include the segment on the Section
303(d) list.
In order to justify a delisting of an AU for a given parameter based on new data, the dataset must be of
sufficient quantity and quality to make an assessment. There are two mechanisms for justifying a delisting
based on assessment results:
• Delisting an AU for all parameters
• Delisting individual parameters for an AU
DWQ will compare the previous IR cycle’s final assessment categories and 303(d) list to the current IR’s
assessment categories and 303(d) list to demonstrate good cause. Where differences in categorical
assignments exist, DWQ will only further investigate the following scenarios for good cause:
• The AU/waterbody or segment within the waterbody was previously not supporting (Category 5) and is
now supporting (Category 1) or shows no evidence of impairment (Category 2).
• The AU/waterbody or segment within the waterbody was previously not supporting but had an approved
TMDL (Category 4A) and is now supporting (Category 1) or shows no evidence of impairment
(Category 2).
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• The AU/waterbody or segment within the waterbody was previously not supporting but had an approved
Category 4B demonstration plan and is now supporting (Category 1) or shows no evidence of
impairment (Category 2).
• The AU/waterbody or segment within the waterbody was previously not supporting but had pollution-
driven impairment (Category 4C) and is now supporting (Category 1) or shows no evidence of
impairment (Category 2).
Note: The next set of scenarios describes the methods that apply to delisting individual parameters rather
than entire AUs.
• A parameter within an AU/waterbody (or segment within the waterbody) was previously not supporting
(Category 5) and is now supporting (Category 1) or shows no evidence of impairment (Category 2).
• A parameter within an AU/waterbody (or segment within the waterbody) was previously not supporting but
had an approved TMDL (Category 4A) and is now supporting (Category 1) or shows no evidence of
impairment (Category 2).
• A parameter within an AU/waterbody (or segment within the waterbody) was previously not supporting but
had an approved Category 4B demonstration plan and is now supporting (Category 1) or shows no
evidence of impairment (Category 2).
• A parameter within an AU/waterbody (or segment within the waterbody) was previously not supporting but
had pollution-driven impairment (Category 4C) and is now supporting (Category 1) or shows no
evidence of impairment (Category 2).
Where assessment category assignments at the AU- and parameter-level warrant a further investigation for
good cause, DWQ will reevaluate the data using the following:
• The period of record from when the AU and/or parameter was first listed
• The period of record in the current assessment cycle
• The data that were collected between when the AU and/or parameter were first listed and the period of
record considered in the current assessment cycle
DWQ will review the data from all assessed sample locations (as defined in Table 4) in the three above
scenarios as part of the demonstration-of-good-cause process to confirm whether there were exceedances at
the sample sites. DWQ must demonstrate that the exceedances no longer exist, no longer are of concern, or
that water quality has improved. DWQ will provide documentation and a justification as to why the site was
not re-sampled and/or whether water quality conditions have improved if a sample site had exceedances and
newer data do not exist. If documentation cannot be provided, the AU and parameter will not be delisted, and
the previous categorical assignment will carry forward.
Delisting Categorical Pollutant Causes
When TMDLs or special studies identify parameters contributing to a cause of impairment that is not the
original cause for listing on the 303(d) list, there may be good cause justification for delisting the categorical
cause if the original impaired parameter is no longer impaired and a linkage of the additional causes can be
documented in a TMDL or other study. For instance, in some circumstances DWQ has identified phosphorus
as a contributing cause of impairment to an existing DO listing and subsequently made a categorical listing for
phosphorus as a cause on subsequent 303(d) lists. Since DWQ does not have assessment methods for
phosphorus, a delisting based on the process outlined here is not feasible. Therefore, if the assessment
results for the original DO listing can justify a delisting, any additional parameters associated with that cause
may also be delisted with proper documentation of a direct linkage.
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Appendix 5 elaborates on the process DWQ will follow when evaluating good cause at the AU-level and also
describes, in more detail, the process DWQ will go through when evaluating good cause at the parameter
level. DWQ applies several delisting codes for EPA review and approval (also included in Appendix 5 ).
If a waterbody or parameter is shown to have good cause for not being listed or removed as an impaired
waterbody or segment within a waterbody on the state’s 303(d) list, DWQ will state the good cause and
provide a detailed description of the good cause. Details of the good-cause evaluation process, such as the
data-analysis work, will not be posted online during the draft public comment period or after the final approval
and publication of the final IR and 303(d) list. DWQ will, however, summarize the data analysis work in the
description of the good cause. The analyses will be available to the public upon request through Utah’s
Government Records Access and Management Act (GRAMA) process.
Previous Categorical Listings
303(d) Listings
DWQ must continue to list all previous impairments absent proper documentation to support changing a
previous not-supporting (Category 5) listing decision to a TMDL-approved (Category 4A), pollution control
(Category 4B), non-pollutant impairment (Category 4C), or delisting (demonstration of good cause). At a
minimum, this includes carrying forward all waterbodies or segments within a waterbody that were previously
not supporting (Category 5), indicating the cause of impairment, listing the beneficial use or uses failing to
meet water quality standards, providing the priority of developing a TMDL, and indicating the assessment
cycle the waterbody or segment within the waterbody was first listed.
Non-303(d) Categorical Listings
Where DWQ has the proper documentation to support changing a previous not-supporting (Category 5) listing
decision to a TMDL-approved (Category 4A), pollution control (Category 4B), non-pollutant impairment
(Category 4C), or delisting (demonstration of good cause), it will do so as outlined by the policies and
procedure described throughout this document.
DWQ will also carry forward all previous categorizations of waterbodies or segments within a waterbody if the
waterbody does not have any credible or representative data from the period of record of the current
assessment cycle. This includes carrying the following forward:
• Previous TMDL-approved (Category 4A), pollution control (Category 4B), and non-pollutant impairment
(Category 4C) categorizations that do not demonstrate good cause.
• Previous categorizations that have insufficient data with exceedances (Category 3), require further
investigations (Category 3), have insufficient data with no exceedances (Category 3), are not
assessed (Category 3), show no evidence of impairment (Category 2), or are supporting (Category
1).
• Historical Category 3 waters that had insufficient data with exceedances will remain in that category unless there is new data for assessment.
Waterbodies or segments within a waterbody that are supporting or show no evidence of impairment
(Categories 1 and 2, respectively) may carry forward for six consecutive assessment (or two rotating basin)
cycles. On the seventh consecutive assessment cycle, DWQ will no longer carry forward a supporting or no
evidence of impairment categorization for waterbodies or segment within a waterbody that do not have any
new data collected in the last 12 years. Data older than the period of record may not be reflective of current
conditions and will not be used for assessment purposes unless there is information or a rationale with
supporting documentation that shows the data are reflective of current conditions.
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If there is evidence that the data are reflective of current conditions, the previous supporting (Category 1) or
no evidence of impairment (Category 2) categorization will carry forward for one more assessment cycle (the
current one) and be re-evaluated in the next cycle. DWQ will not carry forward the supporting or no evidence
of impairment categorization for a seventh consecutive assessment cycle if there is no (or not enough)
supporting evidence that the data are reflective of current conditions. DWQ will instead change the
categorization to insufficient data with no exceedances (Category 3).

303(d) Vision and TMDL Priority Development
DWQ must ensure that TMDLs will be developed following the final release of the current IR and 303(d) list
for waterbodies or segments within a waterbody that are impaired by a pollutant. Recognizing that all TMDLs
cannot be completed at once and that certain risks may be greater than others, CWA Section 303(d) allows
states to prioritize impaired waterbodies or segments within a waterbody on the Section 303(d) list for the
future development of TMDLs.
In 2013, the United States Environmental Protection Agency (EPA) launched a long-term vision and goals effort for the CWA 303(d) program that allowed states to prioritize the 303(d) list of impaired waterbodies for TMDL development. EPA’s Vision 1.0 afforded states the ability to be strategic and focus limited resources on priority waters for more efficient and effective management, with the hope of expeditious achievement of
water quality improvements. As a result, in 2016, DWQ developed Utah’s first prioritization of impaired waters on the 303(d) list for TMDL development. Utah’s Prioritization focused on waterbodies with water
quality impairments that posed the greatest risk to human health.
In 2023, EPA launched Vision 2.0 for the CWA Section 303(d) program, which includes goals related to
planning and prioritization, restoration, protection, data and analysis, and partnerships. It also asked States to consider focus areas including environmental justice, climate change, tribal water quality and program
development and program capacity building. For this iteration, DWQ used Utah’s Prioritization 2.0 as a ten-year road map for water quality restoration and protection planning in the state. In addition to TMDLs, other
complementary planning tools can be used to achieve water quality restoration and protection goals.
For the IR and 303(d) reporting-specific elements, DWQ:
• Assigns TMDL priorities to impaired waterbodies and segments within waterbodies on DWQ’s 303(d) list
• Tracks the status and development of TMDLs

Revision Requests between Cycles
DWQ will, barring unforeseen circumstances, only propose to revise the IR and 303(d) list during the regularly
scheduled reviews, which are currently biennially and on even-numbered years. Interested persons may
petition DWQ at any time to request a revision to the IR and 303(d) list, whether it is an addition or deletion to
the final 303(d) list. DWQ will take the potential revision under strong consideration and begin a dialogue with
the interested party or parties and EPA.
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Literature Cited
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Carlson, R.E., and K.E. Havens. 2005. Simple graphical method for interpretation of relationships between
trophic state variables. Lake and Reservoir Management 21:107-118.
EPA. 2016. Human health recreational ambient water quality criteria or swimming advisories for Microcystins
and Cylindrospermopsin.
Hawkins, C.P., 2006. Quantifying biological integrity by taxonomic completeness: its utility in regional and
global assessments. Ecological Applications, 16(4), pp.1277-1294.
Hawkins, C.P., Olson, J.R. and Hill, R.A., 2010. The reference condition: predicting benchmarks for ecological
and water-quality assessments. Journal of the North American Benthological Society, 29(1), pp.312-343.
Hawkins, C.P., Cao, Y. and Roper, B., 2010. Method of predicting reference condition biota affects the
performance and interpretation of ecological indices. Freshwater Biology, 55(5), pp.1066-1085.
Hughes, R.M., D.P. Larsen, and J.M. Omernik. 1986. Regional reference sites: a method for assessing
stream potential. Environmental Management 5:629–635.
Lévesque, B., M. Gervais, P. Chevalier, D. Gauvin, E. Anassour-laouan-sidi, S. Gingras, N. Fortin, G. Brisson,
C. Greer, and D. Bird. 2014. Science of the Total Environment Prospective study of acute health effects in
relation to exposure to cyanobacteria. Science of the Total Environment 466-467:397–403.
Lin, C. J., T. J. Wade, E. A. Sams, A. P. Dufour, A. D. Chapman, and E. D. Hilborn. 2016. A Prospective
Study of Marine Phytoplankton and Reported Illness among Recreational Beachgoers in Puerto Rico, 2009.
Ostermiller, J. D., M. Shupryt, M. A. Baker, B. Neilson, E. B. Gaddis, A. J. Hobson, B. Marshall, T Miller, D.
Richards, N. vonStackelberg. 2014. Technical Basis for Utah’s Nutrient Strategy, Draft Report. Utah Division
of Water Quality.
Suplee, M., R. Sada de Suplee, D. Feldman, and T. Laidlaw. 2005. Identification and Assessment of Montana
Reference Streams: A Follow-Up and Expansion of the 1992 Benchmark Biology Study. Helena, Montana:
Montana Department of Environmental Quality.
U.S. Environmental Protection Agency (EPA). 2019. Recommended Human Health Recreational Ambient
Water Quality Criteria or Swimming Advisories for Microcystins and Cylindrospermopsin. EPA 822-R-19-001.
Available at https://www.epa.gov/sites/default/files/2019-05/documents/hh-rec-criteria-habs-document-
2019.pdf
U.S. Environmental Protection Agency (EPA). 1985. Guidelines for Deriving Numerical National Water Quality
Criteria for the Protection of Aquatic Organisms and their Uses. EPA-PB85-227049.
U.S. Environmental Protection Agency. EPA Requirements for Quality Assurance Project Plans. Office of
Environmental Information. Washington: March 2002. (EPA/240/B-01/003).
U.S. Environmental Protection Agency. Sampling Analysis Plan Guidance and Template, Version 4, General
Projects. Washington: May 2014. (EPA R9QA/009.1).
U.S. Environmental Protection Agency. 2005. Guidance for 2006 assessment, listing and reporting
requirements pursuant to Sections 303(d) and 305(b) of the Clean Water Act. Available at:
https://www.epa.gov/sites/default/files/2015-10/documents/2006irg-report.pdf. Accessed October 25, 2024.
80
U.S. Geological Survey (USGS). 2006. Guidelines and Standard Procedures for Continuous Water-Quality
Monitors: Station Operation, Record Computation, and Data Reporting. Available at:
http://pubs.usgs.gov/tm/2006/tm1D3/pdf/TM1D3.pdf. Accessed October 25, 2024.
Utah Division of Water Quality (DWQ). 2022. Sample Analysis Plan for Sample Collection and Identification of
Harmful Algal Blooms. Available on DWQ’s Monitoring webpage.
Utah Division of Water Quality (DWQ). 2014. Quality Assurance Program Plan For Environmental Data
Operations. Final Plan. Available on DWQ’s Monitoring webpage Accessed October 25, 2024.
Utah Division of Water Quality (DWQ). 2016. Prioritizing Utah’s 303(D) List.
Wright, J.F. 1995. Development and use of a system for predicting the macroinvertebrate fauna in flowing
waters. Australian Journal of Ecology 20:181–197.
81
Appendix 1
Data Quality Guideline Examples
DWQ Sampling Analysis Plan Requirements
Revision 2 January 1, 2017
Utah Division of Water Quality
Checklist of Essential Elements for Sampling and Analysis Plans (SAPs)
Monitoring Project/Program:
Preparer(s):
Reviewer(s):
Date Submitted for Review:
Date of Review:
Parent QAPP or Equivalent Document:
Instructions for Preparers:
As required by DWQ’s Quality Assurance Program Plan for Monitoring Programs (DWQ QAPP), any monitoring activity
conducted or overseen by DWQ must have a SAP, excluding one-time response actions (such as a spill) or compliance
sampling. The SAP must be reviewed and revised for each field season/monitoring year. SAPs are approved and kept on
file by the Monitoring Section QA Staff and must be distributed to everyone involved with a monitoring project. Provided
below is a template and checklist to create a SAP. The SAP should contain or reference all the elements in this checklist but
need not have the same format. Rather than extensive text, include as much information as possible in the form of tables,
which are easier to refer to in the field. The SAP should be a usable, stand-alone document that can be taken into the field
by Monitors.
Definitions and Acronyms:
DPM - Designated Project Manager. As defined by DEQ’s Quality Management Plan (QMP), the DPM is the staff member
responsible for a specific project and has immediate managerial or technical control of that project. The DPM is responsible
for specifying the quality of the data required for each project and initiating corrective actions when quality control is not being
met. The DPM may also be a program manager. The DPM is responsible for designing monitoring strategies, setting project-
specific data quality objectives (DQOs), and developing project-specific SAPs. DPMs are responsible for making sure all
personnel involved with the project are briefed and/or trained on the procedures to be used. Roles of DPMs are further
discussed throughout the DWQ QAPP.
IR-Integrated Report
SMP – Strategic Monitoring Plan
Introduction and Background Information (This can be brief if it references some previous
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documentation or the IR or SMP, etc.)
• Site history
• Regulatory framework
• Summary of previous investigations
• Location/characteristics of any known pollution sources at the site or in the area
• Site location map showing area at a broad scale
Objectives and Design of the Investigation (This should be very specific to the project and
should be a result of discussions between DPM, data users, stakeholders, science panel, etc.)
• Specific objectives of this study (describe how they support broader program goals/objectives or regulatory framework)
• Provide the study design (i.e. spatial/temporal limits, sample characteristics, the smallest population,
area, volume, or time frame for which decisions will be made).
• Discuss representative sampling conditions and instructions for field personnel if they encounter non-
representative sampling conditions
• Describe parameters of concern (narrative – must conform to list(s) in sections 4 and 6)
• Number, location, and frequency of samples and quality control samples
• Sampling Site Locations
• Rationale for site selection
• Site map(s) showing sampling locations and “control” sites and any other pertinent features such as land
use, etc. within the sampling area
Special Precautions and Safety Plan
• Detailed itemization of any specific safety concerns
• Reference to an applicable safety plan
• Any additional safety training required for project
• Documentation that field personnel comply with your Invasive Species Plan and SOPs to prevent spread of invasive species
Field Sampling Methods and Documentation
• Any special training needed beyond those discussed in DWQ QAPP and where training documentation
will be kept
• Include a table listing each field instrument to be used (equipment, describe operation or indicate where
operation manual is kept for field event, include calibration procedures, if any)
• Include a table listing each sampling method to be used (sampling equipment if needed, cite method in
SAP, attach applicable SOPs)
• For any sampling equipment used, describe operation of any sampling equipment used or location of
operation manual for field event, include decontamination procedures, if any, attach applicable SOPs
• If not found in SOPs, include equipment lists and sampling trip organizing checklists if not found in SOPs
• List corrective actions for problems that may occur in the field
• Discuss what field documentation is required and how field records shall be generated and stored
Laboratory Sample Handling Procedures
• Describe sample containers, preservatives, holding times
• Describe field documentation (COC) and sample labeling procedures
• Describe shipping plan for sample transport to laboratory
Analytical Methods and Laboratory Documentation
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• Chemical – list parameter, cite preparation method and analytical method, list required sensitivity or detection limits
• Biological – cite method or desired taxonomic level and organism target count, etc.
• Required reporting procedures (e.g. hardcopy, electronic deliverables) and turn-around times
• Be sure DWQ has obtained QA documentation for each laboratory used (check with Monitoring Section
QA Staff), reference this information and any new/research analytical methods being used (obtain these
protocols if available from lab)
• List the required data package contents from the analyzing laboratories [or reference a service contract or Memorandum of Understanding (MOU)]
Project Quality Control Requirements
• Table of QC limits for field instruments (operation range, accuracy, and precision)
• Table listing each Data Quality Indicator (precision, accuracy, bias, etc.), how it will be measured, and the
performance criteria against which it will be evaluated (use the table in the DWQ QAPP and adapt it to this
project if needed): (1) analytical (internal to lab) QC limits for chemical analyses (acceptable precision,
accuracy, and negative control – lab method blank, (2) field sample QC limits for chemical analyses
[Acceptable precision (field duplicates) and negative control (field or trip blanks)], and (3) QC limits for
biological analysis [Acceptable precision (% diff in enumeration, 5 taxonomic difference)]
• QC limits, schedule, and descriptions of planned field/lab audits/assessments
• Data quality assurance review procedures: (1) describe system of data qualification, (2) describe measure of completeness relative to planned design, and (3) corrective actions for non-conformance
Data Analysis, Record Keeping, and Reporting Requirements
• Data interpretation approach (include means to temper decision-making if limited completeness of design
occurs)
• Describe project record keeping procedures and archive (hardcopies, electronic data)
• Describe how and when DPM wishes to be notified of available laboratory/field results
• Describe expected content and format of final project report and who will receive original/copies.
Schedule and Budget
• Table or figure showing project schedule with key project milestones
• List funding sources for project and include anticipated equipment, consumables, personnel
purchases/costs
• Sample costs/lab resources per fee schedule
Project Team and Responsibilities
• Identify project team responsibilities and personnel
• Identify sampling personnel
• Identify subcontractors (e.g. chemical and biological labs)
References (include references to DWQ-prepared documents)
Appendices and Attachments (include SOPs, Chain of Custody forms, Field Forms, Sample
Labels, etc.)

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Appendix 2
Application of Secondary Review Process
The table below contains a set of data considerations and concerns that may prompt a change to an
assessment unit category during the secondary review process.
Table 17. Application of secondary review process
Data Concern Secondary Review Process Data Application
Temporal variation within a dataset Insufficient sampling frequency within an assessment period of record Individual data records

Bias in sampling design
(1) Event monitoring (review flow, weather, and spill/response/incident data; narrative criteria; field observations and photographs; satellite imagery; other data types collected in same (and around the) period of concern, etc.), (2) sample time of day (literature review to determine if
parameter is impacted by the time of day sample is collected), (3) sampling a specific season (unless approved by DWQ in a SAP or is data- type specific (e.g., E. coli sampling during the recreation season)], (4) and locational bias

Individual data records

Data quality
(1) Quality Assurance Program Plan For
Environmental Data Operations, (2) field calibration documentation, (3) laboratory
methods, (4) standard operating procedures, (5) demonstration of capability (if applicable to data type), and (6) discussion with sample collector
Individual data records, and/or, parameter(s) in period of record, and/or monitoring location

Wrongly monitored
(1) Measured point source (vs. main water body), review imagery of area, flow, etc., (2) waterbody
type DWQ does not assess, (3) grab sample vs. composite, (4) flow conditions (too low or not flowing), and (5) field observation that impacts quality of data
Individual data records and/or monitoring location

Outlier
(1) Need more than a statistical test. Should be based on scientific or QA basis, (2) QA/QC field sampling blanks, duplicates/replicate, (3) laboratory Analytical Batch QC, (4) value is nonsensical (e.g., cannot be measured with field/laboratory method), and (5) refer to data quality (above)

Individual data records
Magnitude of exceedance (1) Significant figures and (2) narrative criteria review Individual data records
QA/QC concerns (1) Holding time, (2) laboratory comment, (3) dilutions, spikes, and (4) other laboratory QC performance checks Individual data records

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Data Concern Secondary Review Process Data Application

Assessment unit grouping/spatial variation
(1) Multiple locations not grouped correctly (either should or should not have been grouped), (2) AUs where water quality criterion exceedances are clearly isolated to a relatively small, hydrologically distinct portion of the larger AU and may need to be re-segmented to more accurately reflect that variation in water quality (please refer to 303(d) Assessment Methods section on “Assessment Unit Re-segmentation” for more information on the process), and (3) a surface water (e.g., a spring or seep) was sampled in the AU and was assessed but additional information indicates that the surface water may not have been flowing or did not connect, contribute, or influence downstream water quality

Monitoring location

Credible data
(1) Data type applied incorrectly and (2) data type not considered. (Data type must meet credible and representative data requirements in 303(d) Assessment Methods, and if included in the assessment analysis would result in a change in the categorization of the waterbody and parameter
Individual data records and/or parameter(s) in period of record, monitoring location
Other
(1) Parameters wrongly grouped (by CAS, fraction, or methods), (2) data type is laboratory measurement (when the data assessment requires a field measurement), (3) IR QA/QC flagged data, and (4) errors in standards
Individual data records. Entire parameter assessments
Conflicting DO assessments between grab and high frequency data
Scenario: Two types of data available at the site(s) (i.e., grab or high frequency data) do not
have the same preliminary assessment result. Reviews to consider: (1) sampling period
captured, (2) duration of conditions below criterion, (3) frequency of recurrent low DO
events, (4) magnitude of exceedance, (5) spatial extent of low DO, and (6) diel flux of DO

Individual data records. Entire parameter assessments

Conflicting Max Temperature grab assessments and high frequency data
Scenario: Two types of data available at the site(s) (i.e., grab or high frequency data) do not have the same preliminary assessment result. Reviews to consider: (1) sampling period captured, (2) duration of conditions above criterion, (3) frequency of recurrent high temperature events, (4) magnitude of exceedance, (5) spatial extent of high temperature and (6) diel flux of temperature

Individual data records. Entire parameter assessments

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Data Concern Secondary Review Process Data Application

Representativeness and Environmental Factors*
Examples of extreme events include the following: (1) accidental spills of toxic chemicals, (2) scouring storm flows that lead to diminished aquatic-life beneficial uses, and (3) extreme drought conditions. Given the scope of these assessments, it is not always possible to identify where such circumstances may be influencing a specific sample, but DWQ will consider any evidence presented that a sample is not representative of ambient conditions. Examples of such a review may include reviewing flow, weather, spill data, narrative criteria, field observations and photographs, satellite imagery, other data types collected in the same (and around the) period of concern, etc.

Individual data records

Pollution Indicators

Secondary reviewers will incorporate pollution
indicator data into assessment category determinations, relying on multiple lines of
evidence, including pollution indicator thresholds, the presence or absence of other
indicator-associated water quality issues, potential pollutant sources, and other site or
watershed-specific knowledge to determine whether listing or delisting on a pollution
indicator parameter is appropriate or whether to prioritize waterbodies for additional monitoring.
(1) Pollution indicator evaluations will be posted with the report(s (e.g. exceedance counts & frequencies), so DWQ programs and stakeholders can consider the results when planning for future monitoring, studies, evaluations, etc, (2) pollution Indicator evaluations may be included in a narrative assessment/standard not supporting or supporting assessment decision, (3) pollution indicators may be reported by the IR as a cause of pollution impairment, and (4) pollution indicators may be reported by the IR as the source of an impairment

*Footnote: Where these conditions are present in a dataset, DWQ will run the analysis without the extreme events/data record and will apply and document an appropriate assessment result for the waterbody using the methods outlined below. Category 1: Supporting: If analyses with and without the extreme events are supporting (Category 1. Category 2: No evidence of impairment: If analyses with the extreme events are supporting (Category 1), but
the analyses without the extreme events show no evidence of impairment (Category 2) Category 2: No evidence of impairment: If analyses with and without the extreme events do not indicate evidence of impairment (Category 2) Category 2: No evidence of impairment: If analyses with the extreme events are evidence of impairment (Category 3 with exceedances), but the analyses without the extreme events show no evidence of impairment (Category 2)
Category 2: No evidence of impairment: If analyses with the extreme events are not supporting (Category 5), but the analyses without the extreme events show no evidence of impairment (Category 2) Category 3: Insufficient Data, Exceedances: If analyses with and without the extreme events show evidence of impairment (Category 3)
Category 3: Insufficient Data, Exceedances: If analyses with the extreme events are not supporting (Category 5), but the analyses without the extreme events are supporting (Category 1)
Category 5: Not supporting: If analyses with the extreme events are evidence of impairment (Category 3), but the analyses without the extreme events are not supporting (Category 5)
Category 5: Not supporting: If analyses with the extreme events are not supporting (Category 5), but the analyses without the extreme events show evidence of impairment (Category 3) Category 5: Not supporting: If analyses with and without the extreme events are not supporting (Category 5)
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Appendix 3
Summarizing Assessments From Site to
Assessment Unit Level
This appendix uses a theoretical assessment unit (see figure below) to demonstrate how DWQ composes the overall assessment unit category using site-level parameter assessments of beneficial use support. The assessment unit (AU) below has four monitoring locations and two beneficial uses.

In this example, the AU has been sampled for two water quality parameters: temperature and pH. Each
heading below corresponds to a table demonstrating the scenario described. In each table, NS means not supporting (or not meeting criteria; impaired), FS means fully supporting (or meeting criteria), and ID means insufficient data.
Not Supporting (EPA Category 5) The AU is categorized as not supporting if ANY site within the AU is not supporting for one or more parameters that are not covered under a TMDL or other pollution control mechanism. In the example scenario below, Site A is not supporting beneficial use 1 based on temperature criteria, but the AU has a TMDL for temperature. Sites B and D are not supporting beneficial use 2 based on pH criteria, and there is no TMDL in place to address pH. Site C is fully supporting beneficial use 1 based on temperature criteria. Because the AU has sites that are not supporting for a parameter that does not have an existing TMDL in place (rows highlighted in orange), the AU has the overall EPA Category 5. Note that this example is intended to show how Category 5 supersedes a TMDL Category 4A in an assessment unit, but any assessment unit with site- use-parameter combinations that are not supporting one or more beneficial uses and have no TMDL associated with any parameters would also fall under Category 5.
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Figure 22 Assessment Unit Decision: Category 5 (Not supporting) for beneficial use 2 based on pH assessment and Category 4A for beneficial use 1 based on temperature assessment. Temperature is associated with an existing TMDL.
TMDL Approved (EPA Category 4A)
The assessment unit falls in the TMDL approved category if it is not supporting for one or more parameters at one or more sites for which the assessment unit has an approved TMDL. In the example scenario below, Site A is not supporting beneficial use 1 for temperature, but there is a TMDL associated with temperature in that assessment unit (row highlighted in green). Note that site C is fully supporting beneficial use 1 based on temperature criteria, but it is still covered by the AU’s temperature TMDL. Because all other beneficial uses and parameters are fully supporting at sites within the AU, the overall AU category is EPA Category 4A.

Insufficient Data (EPA Category 3)
The assessment unit falls into the insufficient data category if an assessment has not been performed on ANY parameters at ANY of the sites in the assessment unit. In the example scenario below, all sites had data associated with either pH or temperature, but not enough data were collected (based on 303(d) assessment methods) at any site over the period of record to fully assess the site-use-parameter
combination (all rows highlighted in blue denoting the site-use-parameter-level insufficient data assessment category). In this case, the overall AU category is EPA Category 3. DWQ also keeps track of any water quality samples that exceeded numeric criteria. These site-use-parameter combinations are usually prioritized for further sampling and a full assessment.
Figure 23 Assessment Unit Decision: Category 4A (Approved TMDL) for beneficial use 1 based on temperature assessment.
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Figure 24 Assessment Unit Decision: Category 3 (Insufficient Data) based on both beneficial uses and parameter assessments at all four sites.
No Evidence of Impairment (EPA Category 2)
The assessment unit falls into the no evidence of impairment category if at least one use at one or more
sites has been assessed and is fully supporting, but one or more uses have not been assessed at ALL sites within the AU. In the example scenario below, sites A, B, and C were sampled for temperature, which is used to assess support for beneficial use 1. Sites A, B, and D were sampled for pH, which is used to assess support for beneficial use 2. At sites A and B, enough pH data were collected to perform
assessments of beneficial use support for use 2. Only one full assessment of beneficial use support at one site is required to represent a full assessment of beneficial use support for the AU. However, no site
had enough data to fully assess temperature and thus beneficial use support for use 1 (rows highlighted in olive green). Because the AU beneficial use category for use 1 is insufficient data and the beneficial
use category for use 2 is fully supporting, the overall assessment unit category is EPA Category 2, no evidence of impairment. Note that in this case, impairment and not supporting are synonymous terms.

Fully Supporting (EPA Category 1)
The assessment unit is fully supporting if all uses have been assessed at AT LEAST one site (Table 5). Note that in this scenario, a site does not need to be fully assessed for all uses, but the AU must contain sites for which each use was fully assessed. In the example scenario below, use 1 was fully assessed using temperature data at Site A, and use 2 was fully assessed with pH data at Site B. Although some site-use- parameter level datasets had insufficient data to be fully assessed, both beneficial uses were fully assessed at one or more sites within the AU (rows highlighted in light blue), and can be used together to represent a full assessment of the AU’s beneficial uses.
Figure 25 Assessment Unit Decision: Category 2 (No Evidence of Impairment) due to full support of beneficial use 1 based on the pH assessments and insufficient data to assess beneficial use 2 across all sites.
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Figure 26 Assessment Unit Decision: Category 1 (Fully Supporting) for beneficial uses 1 and 2 based on fully supporting pH and temperature assessments at sites within the assessment unit.
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Appendix 4
4B Submission Policies and Procedures:
Process for Determining Category 4B
Classification
An approved Category 4B demonstration plan is an alternative to listing an impaired segment on the state’s
303(d) list. A Category 4B demonstration plan, when implemented, must ensure that all applicable water
quality standards are met through agreed-upon pollution-control mechanisms within a reasonable time period.
These pollution-control mechanisms can include approved compliance schedules for capital improvements or
plans enforceable under other environmental statutes (such as Comprehensive Environmental Response,
Compensation, and Liability Act) and their associated regulations. A Category 4B demonstration can be used
for segments impaired by point sources and/or nonpoint sources. Both DWQ and EPA must accept a
Category 4B demonstration plan for the affected segment to be placed in Category 4B. In the event that the
Category 4B demonstration plan is not accepted, the segment at issue will be included on the 303(d) list,
Category 5.
Generally speaking, the following factors will be considered necessary for Category 4B demonstration plan
acceptance: 1) appropriate voluntary, regulatory, or legal authority to implement the proposed control
mechanisms through permits, grants, compliance orders for Utah Pollutant Discharge Elimination System
permits, etc.; 2) existing commitments by the proponent(s) to implement the controls; 3) adequate funding;
and 4) other relevant factors appropriate to the segment.
The following evidence must be provided as a rationale for a Category 4B demonstration plan:
A statement of the problem causing the impairment
1. A description of
a. The pollution controls to be used
b. How these pollution controls will achieve attainment with all applicable water quality
standards
c. Requirements under which those pollution controls will be implemented
2. An estimate of the time needed to meet all applicable water quality standards.
3. A schedule for implementation of the necessary pollution controls.
4. A schedule for tracking progress, including a description of milestones.
5. A commitment from the demonstration plan proponent to revise the implementation strategy and
pollution controls if progress toward meeting all applicable water quality standards is not shown.
Timing for proposal submittal and acceptance by DWQ and EPA
• Category 4B demonstration plans must be reviewed and approved by both DWQ and EPA for the waterbody to be categorized as 4B in the IR. Parties are encouraged to work with DWQ as states are the entity required to submit these plans to EPA.
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• Acceptance from EPA must be obtained before the IR is finalized, otherwise, DWQ will continue to propose that the segment in question is included on the current cycle’s 303(d) list.
• If EPA and DWQ accept the Category 4B plan, DWQ will notify the Water Quality Board and the public through proposed statement of basis and purpose language in its proposal that a Category 4B demonstration plan is accepted and is appropriate for this segment.
EPA has several documents that contain additional information on Category 4B demonstration requirements,
including: “2006 Integrated Report Guidance”; and “Information Concerning 2008 Clean Water Act Sections
303(d), 305(b), and 314 Integrated Reporting and Listing Decisions”.
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Appendix 5
Delisting Guidelines
DWQ must follow a consistent, well-documented delisting process to be approved by the EPA each cycle. The guidelines below outline the questions and scenarios DWQ considers when analyzing whether sufficient evidence exists to delist a waterbody for one or more pollutants. Does the AU/AU-parameter combination warrant further investigation? (See 303(d) Assessment Methods for more details).
• Generally, this means that the AU was previously listed for one or more parameters that were not meeting
criteria, but in the current assessment, parameter data are meeting criteria and fully supporting at the site- level.
What was the original cause of impairment for the AU?
What beneficial use was assessed? Is it the correct beneficial use? What IR assessment cycle was the AU and parameter first listed?
• What datasets were used for that listing (e.g., the agency/sample collector)?
• What was the period of record? (If unknown, use the longer period of record).
• What MLIDs are in the AU?
For impairments listed in a previous assessment cycle, compile data from all MLIDs in the AU, regardless of waterbody type. Which MLID(s) have/had exceedances in the pollutant of interest?
• For MLIDs with impairments/exceedances that were not assessed in the current IR cycle, determine why the site was not resampled. If the AU is a delisting candidate, provide documentation as to why resampling was not done and why the site should meet water quality standards. Please refer to the good cause descriptions in the 303(d) methods. If the delisting reason does not demonstrate good cause, the documentation will need to be EPA-approved.
• For MLIDs with historical or current impairments/exceedances assessed in the current IR cycle, DWQ will typically not delist an AU where the current parameter assessment for the MLID(s) is not fully supporting. However, DWQ will consider delisting when a secondary review applied to the parameter, MLID, or AU places it in the fully supporting category (or no evidence of impairment at the AU-level). The secondary review justification will need to be EPA-approved and checked for good cause.
• Determine if the current parameter assessment is fully supporting (no secondary review applied to this
parameter) and check for good cause. Consider: What is the oldest date in that period of record for that MLID/Parameter combo in the current assessment cycle?
• Note: Confirm that if no new data are collected, the new assessment analysis is not fully supporting because the exceedances are out of the period of record for assessment analysis. This is not a delisting.
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EPA Delisting Codes
Table 18. Description of EPA Delisting Codes Delisting Reason Code Comment
WQS_NO_LONGER_THREATENED Applicable WQS attained; threatened water no longer threatened
WQS_NEW_ASMT_METHOD Applicable WQS attained, according to new assessment method DELISTING_4C Not caused by a pollutant (4c) DELISTING_WQS_NOT_APPLICABLE WQS no longer applicable
DELISTING_4B Other pollution control requirements (4b)
DELISTING_4A TMDL Approved or established by EPA (4a)
WQS_NEW_DATA Applicable WQS attained; based on new data
WQS_LISTING_INCORRECT Applicable WQS attained; original basis for listing was incorrect REFINEMENT Clarification of listing cause WQS_RESTORATION_ACTIVITIES Applicable WQS attained, due to restoration activities
WQS_RECOVERY_UNSPECIFIED Applicable WQS attained; reason for recovery
unspecified DELISTING_NOT_IN_JURISDICTION Listed water not in state's jurisdiction WQS_STANDARDS_CHANGED Applicable WQS attained, due to change in WQS NOT_SPECIFIED Not specified DELISTING_NOT_WATER_OF_STATE Water determined to not be a water of the state DELISTING_ORIG_INCORRECT Data and/or information lacking to determine WQ status; original basis for listing was incorrect