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Utah Division of Water Quality
Statement of Basis
ADDENDUM
Wasteload Analysis and Antidegradation Level I Review
Date: April 16, 2025
Prepared by: Suzan Tahir
Standards and Technical Services
Facility: Castle Dale Wastewater Treatment Facility
Castle Valley Special Service District
UPDES No. UT0026663
Receiving water: Cottonwood Creek (2B, 3C, 4)
This addendum summarizes the wasteload analysis that was performed to determine water quality
based effluent limits (WQBEL) for this discharge. Wasteload analyses are performed to determine
point source effluent limitations necessary to maintain designated beneficial uses by evaluating
projected effects of discharge concentrations on in-stream water quality. The wasteload analysis
also takes into account downstream designated uses (UAC R317-2-8). Projected concentrations
are compared to numeric water quality standards to determine acceptability. The numeric criteria
in this wasteload analysis may be modified by narrative criteria and other conditions determined
by staff of the Division of Water Quality.
Discharge
Outfall 001: Cottonwood Creek
The maximum daily design discharge is 0.95 MGD and the maximum monthly design discharge
is 0.70 MGD for the facility.
Receiving Water
The receiving water for Outfall 001 is Cottonwood Creek, which is tributary to Huntington Creek,
which drains to the San Rafael River and the Colorado River.
Per UAC R317-2-13.1(b), the designated beneficial uses for Cottonwood Creek from confluence
with Huntington Creek to Highway U-57 crossing are 2B, 3C and 4.
● Class 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.
● Class 3C - Protected for nongame fish and other aquatic life, including the necessary aquatic
organisms in their food chain.
● Class 4 - Protected for agricultural uses including irrigation of crops and stock watering.
Utah Division of Water Quality
Wasteload Analysis
Castle Dale Wastewater Treatment Facility
UPDES No. UT0026663
Page 2 of 4
Critical Flow
Typically, the critical flow for the wasteload analysis is considered the lowest stream flow for
seven consecutive days with a ten-year return frequency (7Q10). Due to a lack of flow records for
Cottonwood Creek, the 20th percentile of flow measurements taken upstream of the outfall at the
Highway U-10 crossing was calculated to estimate annual critical flow in the receiving water
(Table 1).
Table 1: Annual critical low flow for Cottonwood Creek at U-10 crossing
Season Flow (cfs)
Annual 1.71
Receiving water quality data were obtained from monitoring site COTTONWOOD CK BL U10
XING IN CASTLEDALE for the period 2015-2025. The average seasonal value was calculated
for each constituent with available data in the receiving water.
Effluent parameters were characterized using data from monitoring site 4930900 Castle Dale
Lagoons Outfall for the period 2015-2025.
Mixing Zone
Per UAC R317-2-5, a discharge is considered instantaneously fully mixed if the discharge is more
than twice the ambient flow. Therefore, no mixing zone is granted for this discharge.
Parameters of Concern
The potential parameters of concern identified for the discharge/receiving water were total
suspended solids (TSS), total dissolved solids (TDS), dissolved oxygen (DO), Biochemical
Oxygen Demand (BOD5), total phosphorus (TP), total nitrogen (TN), total ammonia (NH3-N), E.
coli, pH, and total residual chlorine (TRC) as determined in consultation with the UPDES Permit
Writer.
TMDL
Cottonwood Creek from the confluence with Huntington Creek to Highway 57 (UT14060009-
011_00) was listed as impaired for pH and total dissolved solids according to the 303(d) list in
Utah’s 2024 Integrated Report.
Protection of Downstream Uses
Per UAC R317-2-8, all actions to control waste discharges under these rules shall be modified as
necessary to protect downstream designated uses. For this discharge, 3C numeric aquatic life use
criteria apply to the immediate receiving water (Cottonwood Creek).
Utah Division of Water Quality
Wasteload Analysis
Castle Dale Wastewater Treatment Facility
UPDES No. UT0026663
Page 3 of 4
Site Specific Total Dissolved Solids Criterion
Per UAC R317-2-14, Cottonwood Creek from the confluence with Huntington Creek to U-57 has
a site-specific criterion for TDS concentration of 3,500 mg/L that is based upon the EPA approved
Total Maximum Daily Load (TMDL) Price River, San Rafael River, and Muddy Creek TMDLs
for Total Dissolved Solids, West Colorado Watershed Management Unit, Utah (MFG Inc., 2004).
WET Limits
The percent of effluent in the receiving water in a fully mixed condition, and acute and chronic
dilution in a not fully mixed condition are calculated in the WLA in order to generate WET limits.
The LC50 (lethal concentration, 50%) percent effluent for acute toxicity and the IC25 (inhibition
concentration, 25%) percent effluent for chronic toxicity, as determined by the WET test, needs to
be below the WET limits, as determined by the WLA. The WET limit for LC50 is typically 100%
effluent and does not need to be determined by the WLA.
Table 2: WET Limits for IC25
Season Percent
Effluent
Annual 38.8%
Water Quality Modeling
Effluent limits for conservative pollutants were determined using a mass balance mixing analysis
(UDWQ 2012). The inputs and results of the mass balance analysis is summarized in the
Addendum of SOB.
Model and supporting documentation are available for review upon request.
Antidegradation Level I Review
The objective of the Level I ADR is to ensure the protection of existing uses, defined as the
beneficial uses attained in the receiving water on or after November 28, 1975. No evidence is
known that the existing uses deviate from the designated beneficial uses for the receiving water.
Therefore, the beneficial uses will be protected if the discharge remains below the WQBELs
presented in this wasteload.
Antidegradation Level II Review
A Level II Antidegradation Review (ADR) is not required for this discharge since the pollutant
concentration and load is not increasing under this permit renewal.
Utah Division of Water Quality
Wasteload Analysis
Castle Dale Wastewater Treatment Facility
UPDES No. UT0026663
Page 4 of 4
Documents:
WLA Document:
CastleDaleWLA_04-29-2025.docx
Wasteload Analysis:
CastleDaleWLA_04-29-2025.xlsm
CastleDaleWLA_SOB_04-29-2025.pdf
References:
Utah Division of Water Quality. 2024. Final 2024 Integrated Report on Water Quality
Utah Division of Water Quality. 2021. Utah Wasteload Analysis Procedures Version 2.0.
Lewis, B., J. Saunders, and M. Murphy. 2002. Ammonia Toxicity Model (AMMTOX, Version2): A Tool for
Determining Effluent Ammonia Limits. University of Colorado, Center for Limnology.
MFG Inc. 2004. Price River, San Rafael River, and Muddy Creek TMDLs for Total Dissolved Solids, West Colorado
Watershed Management Unit, Utah. Utah Division of Water Quality.
Utah Division of Water Quality
Salt Lake City, Utah
WASTELOAD ANALYSIS [WLA]29-Apr-25
Addendum: Statement of Basis 4:00 PM
Facilities: Castle Dale Lagoons UPDES No:UT-UT-0026663
Discharging to:Cottonwood Creek
I. Introduction
Wasteload analyses are performed to determine point source effluent limitations necessary to maintain designated
beneficial uses by evaluating projected effects of discharge concentrations on in-stream water quality. The
wasteload analysis also takes into account downstream designated uses [R317-2-8, UAC]. Projected concen-
trations are compared to numeric water quality standards to determine acceptability. The anti-degradation
policy and procedures are also considered. The primary in-stream parameters of concern may include metals
(as a function of hardness), total dissolved solids (TDS), total residual chlorine (TRC), un-ionized ammonia (as a
function of pH and temperature, measured and evaluated interms of total ammonia), and dissolved oxygen.
Mathematical water quality modeling is employed to determine stream quality response to point source discharges.
Models aid in the effort of anticipating stream quality at future effluent flows at critical environmental conditions
(e.g., low stream flow, high temperature, high pH, etc).
The numeric criteria in this wasteload analysis may always be modified by narrative criteria and other conditions
determined by staff of the Division of Water Quality.
II. Receiving Water and Stream Classification
Cottonwood Creek:2B, 3C, 4
Antidegradation Review:Level I review completed. Level II review not required.
III. Numeric Stream Standards for Protection of Aquatic Wildlife
Total Ammonia (TNH3)Varies as a function of Temperature and
pH Rebound. See Water Quality Standards
Chronic Total Residual Chlorine (TRC)0.011 mg/l (4 Day Average)
0.019 mg/l (1 Hour Average)
Dissolved Oxygen (DO)5.00 mg/l (30 Day Average)
N/A mg/l (7 Day Average)
3.00 mg/l (Instantaneous)
Maximum Total Dissolved Solids 3500.0 mg/l Background
Acute and Chronic Heavy Metals (Dissolved)
4 Day Average (Chronic) Standard 1 Hour Average (Acute) Standard
Parameter Concentration Load*Concentration Load*
Aluminum 87.00 ug/l**0.508 lbs/day 750.00 ug/l 4.378 lbs/day
Arsenic 150.00 ug/l 0.876 lbs/day 340.00 ug/l 1.985 lbs/day
Cadmium 2.34 ug/l 0.014 lbs/day 7.21 ug/l 0.042 lbs/day
Chromium III 262.96 ug/l 1.535 lbs/day 5501.59 ug/l 32.112 lbs/day
ChromiumVI 11.00 ug/l 0.064 lbs/day 16.00 ug/l 0.093 lbs/day
Copper 29.88 ug/l 0.174 lbs/day 50.52 ug/l 0.295 lbs/day
Iron 1000.00 ug/l 5.837 lbs/day
Lead 18.02 ug/l 0.105 lbs/day 462.35 ug/l 2.699 lbs/day
Mercury 0.0120 ug/l 0.000 lbs/day 2.40 ug/l 0.014 lbs/day
Nickel 165.13 ug/l 0.964 lbs/day 1485.21 ug/l 8.669 lbs/day
Selenium 4.60 ug/l 0.027 lbs/day 18.40 ug/l 0.107 lbs/day
Silver N/A ug/l N/A lbs/day 39.40 ug/l 0.230 lbs/day
Zinc 379.96 ug/l 2.218 lbs/day 379.96 ug/l 2.218 lbs/day
* Allowed below discharge
**Chronic Aluminum standard applies only to waters with a pH < 7.0 and a Hardness < 50 mg/l as CaCO3
Metals Standards Based upon a Hardness of 390.44 mg/l as CaCO3
Page 1
Utah Division of Water Quality
Salt Lake City, Utah
Organics [Pesticides]
4 Day Average (Chronic) Standard 1 Hour Average (Acute) Standard
Parameter Concentration Load*Concentration Load*
Aldrin 1.500 ug/l 0.009 lbs/day
Chlordane 0.004 ug/l 0.065 lbs/day 1.200 ug/l 0.007 lbs/day
DDT, DDE 0.001 ug/l 0.015 lbs/day 0.550 ug/l 0.003 lbs/day
Dieldrin 0.056 ug/l 0.843 lbs/day 0.240 ug/l 0.001 lbs/day
Endosulfan 0.056 ug/l 0.843 lbs/day 0.110 ug/l 0.001 lbs/day
Endrin 0.036 ug/l 0.542 lbs/day 0.086 ug/l 0.001 lbs/day
Guthion 0.010 ug/l 0.000 lbs/day
Heptachlor 0.004 ug/l 0.057 lbs/day 0.260 ug/l 0.002 lbs/day
Lindane 0.080 ug/l 1.204 lbs/day 1.000 ug/l 0.006 lbs/day
Methoxychlor 0.030 ug/l 0.000 lbs/day
Mirex 0.010 ug/l 0.000 lbs/day
Parathion 0.066 ug/l 0.000 lbs/day
PCB's 0.014 ug/l 0.211 lbs/day N/A ug/l #VALUE!lbs/day
Pentachlorophenol 15.00 ug/l 225.774 lbs/day 19.000 ug/l 0.111 lbs/day
Toxephene 0.0002 ug/l 0.003 lbs/day 0.7300 ug/l 0.004 lbs/day
IV. Numeric Stream Standards for Protection of Agriculture
4 Day Average (Chronic) Standard 1 Hour Average (Acute) Standard
Concentration Load*Concentration Load*
Arsenic 100.0 ug/l lbs/day
Boron 750.0 ug/l lbs/day
Cadmium 10.0 ug/l 0.03 lbs/day
Chromium 100.0 ug/l lbs/day
Copper 200.0 ug/l lbs/day
Lead 100.0 ug/l lbs/day
Selenium 50.0 ug/l lbs/day
TDS, Summer 3500.0 mg/l 10.21 tons/day
V. Numeric Stream Standards for Protection of Human Health (Class 1C Waters)
4 Day Average (Chronic) Standard 1 Hour Average (Acute) Standard
Metals Concentration Load*Concentration Load*
Arsenic ug/l lbs/day
Barium ug/l lbs/day
Cadmium ug/l lbs/day
Chromium ug/l lbs/day
Lead ug/l lbs/day
Mercury ug/l lbs/day
Selenium ug/l lbs/day
Silver ug/l lbs/day
Fluoride (3)ug/l lbs/day
to ug/l lbs/day
Nitrates as N ug/l lbs/day
Chlorophenoxy Herbicides
2,4-D ug/l lbs/day
2,4,5-TP ug/l lbs/day
Endrin ug/l lbs/day
Hexachlorocyclohexane (Lindane)ug/l lbs/day
Methoxychlor ug/l lbs/day
Toxaphene ug/l lbs/day
Page 2
Utah Division of Water Quality
Salt Lake City, Utah
VI. Numeric Stream Standards the Protection of Human Health from Water & Fish Consumption [Toxics]
Maximum Conc., ug/l - Acute Standards
Class 1C Class 3A, 3B
Toxic Organics [2 Liters/Day for 70 Kg Person over 70 Yr.] [6.5 g for 70 Kg Person over 70 Yr.]
Acenaphthene ug/l lbs/day 90.0 ug/l 1.35 lbs/day
Acrolein ug/l lbs/day 400.0 ug/l 6.02 lbs/day
Acrylonitrile ug/l lbs/day 7.0 ug/l 0.11 lbs/day
Benzene ug/l lbs/day 51.0 ug/l 0.77 lbs/day
Benzidine ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Carbon tetrachloride ug/l lbs/day 5.0 ug/l 0.08 lbs/day
Chlorobenzene ug/l lbs/day 800.0 ug/l 12.04 lbs/day
1,2,4-Trichlorobenzene
Hexachlorobenzene ug/l lbs/day 0.0 ug/l 0.00 lbs/day
1,2-Dichloroethane ug/l lbs/day 2000.0 ug/l 30.10 lbs/day
1,1,1-Trichloroethane
Hexachloroethane ug/l lbs/day 0.1 ug/l 0.00 lbs/day
1,1-Dichloroethane
1,1,2-Trichloroethane ug/l lbs/day 8.9 ug/l 0.13 lbs/day
1,1,2,2-Tetrachloroethane ug/l lbs/day 3.0 ug/l 0.05 lbs/day
Chloroethane 0.0 ug/l 0.00 lbs/day
Bis(2-chloroethyl) ether ug/l lbs/day 2.2 ug/l 0.03 lbs/day
2-Chloroethyl vinyl ether ug/l lbs/day 0.0 ug/l 0.00 lbs/day
2-Chloronaphthalene ug/l lbs/day 1000.0 ug/l 15.05 lbs/day
2,4,6-Trichlorophenol ug/l lbs/day 2.8 ug/l 0.04 lbs/day
p-Chloro-m-cresol 0.0 ug/l 0.00 lbs/day
Chloroform (HM)ug/l lbs/day 2000.0 ug/l 30.10 lbs/day
2-Chlorophenol ug/l lbs/day 800.0 ug/l 12.04 lbs/day
1,2-Dichlorobenzene ug/l lbs/day 3000.0 ug/l 45.15 lbs/day
1,3-Dichlorobenzene ug/l lbs/day 10.0 ug/l 0.15 lbs/day
1,4-Dichlorobenzene ug/l lbs/day 900.0 ug/l 13.55 lbs/day
3,3'-Dichlorobenzidine ug/l lbs/day 0.2 ug/l 0.00 lbs/day
1,1-Dichloroethylene ug/l lbs/day 20000.0 ug/l 301.03 lbs/day
1,2-trans-Dichloroethylene1 ug/l lbs/day 4000.0 ug/l 60.21 lbs/day
2,4-Dichlorophenol ug/l lbs/day 60.0 ug/l 0.90 lbs/day
1,2-Dichloropropane ug/l lbs/day 31.0 ug/l 0.47 lbs/day
1,3-Dichloropropylene ug/l lbs/day 1700.0 ug/l 25.59 lbs/day
2,4-Dimethylphenol ug/l lbs/day 3000.0 ug/l 45.15 lbs/day
2,4-Dinitrotoluene ug/l lbs/day 1.7 ug/l 0.03 lbs/day
2,6-Dinitrotoluene ug/l lbs/day 0.0 ug/l 0.00 lbs/day
1,2-Diphenylhydrazine ug/l lbs/day 0.2 ug/l 0.00 lbs/day
Ethylbenzene ug/l lbs/day 130.0 ug/l 1.96 lbs/day
Fluoranthene ug/l lbs/day 20.0 ug/l 0.30 lbs/day
4-Chlorophenyl phenyl ether
4-Bromophenyl phenyl ether
Bis(2-chloroisopropyl) ether ug/l lbs/day 65000.0 ug/l 9.78E+02 lbs/day
Bis(2-chloroethoxy) methane ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Methylene chloride (HM)ug/l lbs/day 1000.0 ug/l 15.05 lbs/day
Methyl chloride (HM)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Methyl bromide (HM)ug/l lbs/day 10000.0 ug/l 150.52 lbs/day
Bromoform (HM)ug/l lbs/day 120.0 ug/l 1.81 lbs/day
Dichlorobromomethane(HM)ug/l lbs/day 27.0 ug/l 0.41 lbs/day
Chlorodibromomethane (HM)ug/l lbs/day 21.0 ug/l 0.32 lbs/day
Hexachlorobutadiene(c)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Hexachlorocyclopentadiene ug/l lbs/day 4.0 ug/l 0.06 lbs/day
Isophorone ug/l lbs/day 1800.0 ug/l 27.09 lbs/day
Naphthalene
Nitrobenzene ug/l lbs/day 600.0 ug/l 9.03 lbs/day
2-Nitrophenol ug/l lbs/day 0.0 ug/l 0.00 lbs/day
4-Nitrophenol ug/l lbs/day 0.0 ug/l 0.00 lbs/day
2,4-Dinitrophenol ug/l lbs/day 14000.0 ug/l 210.72 lbs/day
4,6-Dinitro-o-cresol ug/l lbs/day 765.0 ug/l 11.51 lbs/day
N-Nitrosodimethylamine ug/l lbs/day 3.0 ug/l 0.05 lbs/day
N-Nitrosodiphenylamine ug/l lbs/day 6.0 ug/l 0.09 lbs/day
N-Nitrosodi-n-propylamine ug/l lbs/day 0.5 ug/l 0.01 lbs/day
Pentachlorophenol ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Phenol ug/l lbs/day 3.0E+05 ug/l 4.52E+03 lbs/day
Bis(2-ethylhexyl)phthalate ug/l lbs/day 0.4 ug/l 0.01 lbs/day
Butyl benzyl phthalate ug/l lbs/day 0.1 ug/l 0.00 lbs/day
Page 3
Utah Division of Water Quality
Salt Lake City, Utah
Di-n-butyl phthalate ug/l lbs/day 30.0 ug/l 0.45 lbs/day
Di-n-octyl phthlate
Diethyl phthalate ug/l lbs/day 600.0 ug/l 9.03 lbs/day
Dimethyl phthlate ug/l lbs/day 2.0E+03 ug/l 3.01E+01 lbs/day
Benzo(a)anthracene (PAH)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Benzo(a)pyrene (PAH)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Benzo(b)fluoranthene (PAH)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Benzo(k)fluoranthene (PAH)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Chrysene (PAH)ug/l lbs/day 0.1 ug/l 0.00 lbs/day
Acenaphthylene (PAH)
Anthracene (PAH)ug/l lbs/day 400.0 ug/l 6.02 lbs/day
Dibenzo(a,h)anthracene (PAH)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Indeno(1,2,3-cd)pyrene (PAH)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Pyrene (PAH)ug/l lbs/day 30.0 ug/l 0.45 lbs/day
Tetrachloroethylene ug/l lbs/day 520.0 ug/l 7.83 lbs/day
Toluene ug/l lbs/day 520 ug/l 7.83 lbs/day
Trichloroethylene ug/l lbs/day 7.0 ug/l 0.11 lbs/day
Vinyl chloride ug/l lbs/day 1.6 ug/l 0.02 lbs/day
lbs/day
Pesticides lbs/day
Aldrin ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Dieldrin ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Chlordane ug/l lbs/day 0.0 ug/l 0.00 lbs/day
4,4'-DDT ug/l lbs/day 0.0 ug/l 0.00 lbs/day
4,4'-DDE ug/l lbs/day 0.0 ug/l 0.00 lbs/day
4,4'-DDD ug/l lbs/day 0.0 ug/l 0.00 lbs/day
alpha-Endosulfan ug/l lbs/day 30.0 ug/l 0.45 lbs/day
beta-Endosulfan ug/l lbs/day 40.0 ug/l 0.60 lbs/day
Endosulfan sulfate ug/l lbs/day 40.0 ug/l 0.60 lbs/day
Endrin ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Endrin aldehyde ug/l lbs/day 1.0 ug/l 0.02 lbs/day
Heptachlor ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Heptachlor epoxide
PCB's
PCB 1242 (Arochlor 1242)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
PCB-1254 (Arochlor 1254)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
PCB-1221 (Arochlor 1221)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
PCB-1232 (Arochlor 1232)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
PCB-1248 (Arochlor 1248)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
PCB-1260 (Arochlor 1260)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
PCB-1016 (Arochlor 1016)ug/l lbs/day 0.0 ug/l 0.00 lbs/day
Pesticide
Toxaphene ug/l 0.0 ug/l 0.00 lbs/day
Dioxin
Dioxin (2,3,7,8-TCDD)ug/l lbs/day
Page 4
Utah Division of Water Quality
Salt Lake City, Utah
Metals
Antimony ug/l lbs/day
Arsenic ug/l lbs/day 640.00 ug/l 9.63 lbs/day
Asbestos ug/l lbs/day
Beryllium
Cadmium
Chromium (III)
Chromium (VI)
Copper
Cyanide ug/l lbs/day 4.0E+02 ug/l 6.02 lbs/day
Lead ug/l lbs/day
Mercury 0.15 ug/l 0.00 lbs/day
Nickel 4600.00 ug/l 69.24 lbs/day
Selenium ug/l lbs/day
Silver ug/l lbs/day
Thallium 0.47 ug/l 0.01 lbs/day
Zinc
There are additional standards that apply to this receiving water, but were not
considered in this modeling/waste load allocation analysis.
VII. Mathematical Modeling of Stream Quality
Model configuration was accomplished utilizing standard modeling procedures. Data points were
plotted and coefficients adjusted as required to match observed data as closely as possible.
The modeling approach used in this analysis included one or a combination of the following
models.
(1) The Utah River Model, Utah Division of Water Quality, 1992. Based upon STREAMDO IV
(Region VIII) and Supplemental Ammonia Toxicity Models; EPA Region VIII, Sept. 1990 and
QUAL2E (EPA, Athens, GA).
(2) Utah Ammonia/Chlorine Model, Utah Division of Water Quality, 1992.
(3) AMMTOX Model, University of Colorado, Center of Limnology, and EPA Region 8
(4) Principles of Surface Water Quality Modeling and Control. Robert V. Thomann, et.al.
Harper Collins Publisher, Inc. 1987, pp. 644.
Coefficients used in the model were based, in part, upon the following references:
(1) Rates, Constants, and Kinetics Formulations in Surface Water Quality Modeling. Environmen-
tal Research Laboratory, Office of Research and Development, U.S. Environmental Protection
Agency, Athens Georgia. EPA/600/3-85/040 June 1985.
(2) Principles of Surface Water Quality Modeling and Control. Robert V. Thomann, et.al.
Harper Collins Publisher, Inc. 1987, pp. 644.
Page 5
Utah Division of Water Quality
Salt Lake City, Utah
VIII. Modeling Information
The required information for the model may include the following information for both the
upstream conditions at low flow and the effluent conditions:
Flow, Q, (cfs or MGD)D.O. mg/l
Temperature, Deg. C.Total Residual Chlorine (TRC), mg/l
pH Total NH3-N, mg/l
BOD5, mg/l Total Dissolved Solids (TDS), mg/l
Metals, ug/l Toxic Organics of Concern, ug/l
Other Conditions
In addition to the upstream and effluent conditions, the models require a variety of physical and
biological coefficients and other technical information. In the process of actually establishing the
permit limits for an effluent, values are used based upon the available data, model calibration,
literature values, site visits and best professional judgement.
Model Inputs
The following is upstream and discharge information that was utilized as inputs for the analysis.
Dry washes are considered to have an upstream flow equal to the flow of the discharge.
Current Upstream Information
Stream Critical
Low Flow Temp.pH T-NH3 BOD5 DO TRC TDS
cfs Deg. C mg/l as N mg/l mg/l mg/l mg/l
Summer 1.71 17.2 8.0 0.03 1.83 7.03 0.00 708.7
Fall 1.71 4.1 8.4 0.03 1.50 --- 0.00 601.3
Winter 1.71 5.2 8.6 0.03 1.50 --- 0.00 523.0
Spring 1.71 9.5 8.4 0.02 1.50 --- 0.00 315.3
Dissolved Al As Cd CrIII CrVI Copper Fe Pb
Metals ug/l ug/l ug/l ug/l ug/l ug/l ug/l ug/l
All Seasons 2.385*0.795*0.0795*0.795*3.975*0.8*1.25*0.795*
Dissolved Hg Ni Se Ag Zn Boron
Metals ug/l ug/l ug/l ug/l ug/l ug/l
All Seasons 0.0000 0.795*1.59*0.25 0.0795*1.59** ~80% MDL
Page 6
Utah Division of Water Quality
Salt Lake City, Utah
Projected Discharge Information
Season Flow, MGD Temp.
Summer 0.70000 11.2
Fall 0.70000 11.2
Winter 0.70000 7.0
Spring 0.70000 12.4
All model numerical inputs, intermediate calculations, outputs and graphs are available for
discussion, inspection and copy at the Division of Water Quality.
IX. Effluent Limitations
Current State water quality standards are required to be met under a variety of conditions including
in-stream flows targeted to the 7-day, 10-year low flow (R317-2-9).
Other conditions used in the modeling effort coincide with the environmental conditions expected
at low stream flows.
Effluent Limitation for Flow based upon Water Quality Standards
In-stream criteria of downstream segments will be met with an effluent flow maximum value as follows:
Season Daily Average
Summer 0.700 MGD 1.083 cfs
Fall 0.700 MGD 1.083 cfs
Winter 0.700 MGD 1.083 cfs
Spring 0.700 MGD 1.083 cfs
Flow Requirement or Loading Requirement
The calculations in this wasteload analysis utilize the maximum effluent discharge flow of 0.7 MGD. If the
discharger is allowed to have a flow greater than 0.7 MGD during 7Q10 conditions, and effluent limit
concentrations as indicated, then water quality standards will be violated. In order to prevent this from occuring,
the permit writers must include the discharge flow limititation as indicated above; or, include loading effluent
limits in the permit.
Effluent Limitation for Whole Effluent Toxicity (WET) based upon WET Policy
Effluent Toxicity will not occur in downstream segements if the values below are met.
WET Requirements LC50 >100.0%Effluent [Acute]
IC25 >38.8%Effluent [Chronic]
Page 7
Utah Division of Water Quality
Salt Lake City, Utah
Effluent Limitation for Biological Oxygen Demand (BOD) based upon Water Quality
Standards or Regulations
In-stream criteria of downstream segments for Dissolved Oxygen will be met with an effluent BOD
limitation as follows:
Season Concentration
Summer 25.0 mg/l as BOD5 145.9 lbs/day
Fall 25.0 mg/l as BOD5 145.9 lbs/day
Winter 25.0 mg/l as BOD5 145.9 lbs/day
Spring 25.0 mg/l as BOD5 145.9 lbs/day
Effluent Limitation for Dissolved Oxygen (DO) based upon Water Quality Standards
In-stream criteria of downstream segments for Dissolved Oxygen will be met with an effluent
D.O. limitation as follows:
Season Concentration
Summer 5.00
Fall 5.00
Winter 5.00
Spring 5.00
Effluent Limitation for Total Ammonia based upon Water Quality Standards
In-stream criteria of downstream segments for Total Ammonia will be met with an effluent
limitation (expressed as Total Ammonia as N) as follows:
Season
Concentration Load
Summer 4 Day Avg. - Chronic 7.33 mg/l as N 42.8 lbs/day
1 Hour Avg. - Acute 27.5 mg/l as N 160.3 lbs/day
Fall 4 Day Avg. - Chronic 6.6 mg/l as N 38.2 lbs/day
1 Hour Avg. - Acute 16.6 mg/l as N 97.0 lbs/day
Winter 4 Day Avg. - Chronic 6.7 mg/l as N 39.2 lbs/day
1 Hour Avg. - Acute 10.9 mg/l as N 63.5 lbs/day
Spring 4 Day Avg. - Chronic 6.5 mg/l as N 38.1 lbs/day
1 Hour Avg. - Acute 14.6 mg/l as N 85.4 lbs/day
Acute limit calculated with an Acute Zone of Initial Dilution (ZID) to be equal to 100.%.
Effluent Limitation for Total Residual Chlorine based upon Water Quality Standards
In-stream criteria of downstream segments for Total Residual Chlorine will be met with an effluent
limitation as follows:
Season Concentration Load
Summer 4 Day Avg. - Chronic 0.032 mg/l 0.19 lbs/day
1 Hour Avg. - Acute 0.034 mg/l 0.20 lbs/day
Fall 4 Day Avg. - Chronic 0.032 mg/l 0.19 lbs/day
1 Hour Avg. - Acute 0.034 mg/l 0.20 lbs/day
Winter 4 Day Avg. - Chronic 0.032 mg/l 0.19 lbs/day
1 Hour Avg. - Acute 0.034 mg/l 0.20 lbs/day
Spring 4 Day Avg. - Chronic 0.032 mg/l 0.19 lbs/day
1 Hour Avg. - Acute 0.034 mg/l 0.20 lbs/day
Page 8
Utah Division of Water Quality
Salt Lake City, Utah
Effluent Limitations for Total Dissolved Solids based upon Water Quality Standards
Season Concentration Load
Summer Maximum, Acute 7906.7 mg/l 23.08 tons/day
Fall Maximum, Acute 8076.2 mg/l 23.57 tons/day
Winter Maximum, Acute 8199.9 mg/l 23.93 tons/day
Spring Maximum, Acute 8527.8 mg/l 24.89 tons/day
Colorado Salinity Forum Limits Determined by Permitting Section
Effluent Limitations for Total Recoverable Metals based upon
Water Quality Standards
In-stream criteria of downstream segments for Dissolved Metals will be met with an effluent
limitation as follows (based upon a hardness of 390.44 mg/l):
4 Day Average 1 Hour Average
Concentration Load Concentration Load
Aluminum*N/A N/A 1,340.1 ug/l 7.8 lbs/day
Arsenic*385.55 ug/l 1.5 lbs/day 607.8 ug/l 3.5 lbs/day
Cadmium 5.91 ug/l 0.0 lbs/day 12.8 ug/l 0.1 lbs/day
Chromium III 676.84 ug/l 2.6 lbs/day 9,843.7 ug/l 57.5 lbs/day
Chromium VI*22.09 ug/l 0.1 lbs/day 25.5 ug/l 0.1 lbs/day
Copper 75.78 ug/l 0.3 lbs/day 89.8 ug/l 0.5 lbs/day
Iron*N/A N/A 1,788.4 ug/l 10.4 lbs/day
Lead 45.21 ug/l 0.2 lbs/day 826.7 ug/l 4.8 lbs/day
Mercury*0.03 ug/l 0.0 lbs/day 4.3 ug/l 0.0 lbs/day
Nickel 424.56 ug/l 1.6 lbs/day 2,656.9 ug/l 15.5 lbs/day
Selenium*9.35 ug/l 0.0 lbs/day 31.7 ug/l 0.2 lbs/day
Silver N/A ug/l N/A lbs/day 70.3 ug/l 0.4 lbs/day
Zinc 979.69 ug/l 3.7 lbs/day 679.8 ug/l 4.0 lbs/day
Cyanide*13.41 ug/l 0.1 lbs/day 39.4 ug/l 0.2 lbs/day
*Limits for these metals are based on the dissolved standard.
Effluent Limitations for Heat/Temperature based upon
Water Quality Standards
Summer 27.5 Deg. C.81.5 Deg. F
Fall 14.5 Deg. C.58.0 Deg. F
Winter 15.5 Deg. C.59.9 Deg. F
Spring 19.8 Deg. C.67.7 Deg. F
Effluent Limitations for Organics [Pesticides]
Based upon Water Quality Standards
In-stream criteria of downstream segments for Organics [Pesticides]
will be met with an effluent limit as follows:
4 Day Average 1 Hour Average
Concentration Load Concentration Load
Aldrin 1.5E+00 ug/l 1.35E-02 lbs/day
Chlordane 4.30E-03 ug/l 2.51E-02 lbs/day 1.2E+00 ug/l 1.08E-02 lbs/day
DDT, DDE 1.00E-03 ug/l 5.84E-03 lbs/day 5.5E-01 ug/l 4.97E-03 lbs/day
Dieldrin 5.60E-02 ug/l 3.27E-01 lbs/day 2.4E-01 ug/l 2.17E-03 lbs/day
Endosulfan 5.60E-02 ug/l 3.27E-01 lbs/day 1.1E-01 ug/l 9.93E-04 lbs/day
Endrin 3.60E-02 ug/l 2.10E-01 lbs/day 8.6E-02 ug/l 7.77E-04 lbs/day
Guthion 0.00E+00 ug/l 0.00E+00 lbs/day 1.0E-02 ug/l 9.03E-05 lbs/day
Heptachlor 3.80E-03 ug/l 2.22E-02 lbs/day 2.6E-01 ug/l 2.35E-03 lbs/day
Lindane 8.00E-02 ug/l 4.67E-01 lbs/day 1.0E+00 ug/l 9.03E-03 lbs/day
Methoxychlor 0.00E+00 ug/l 0.00E+00 lbs/day 3.0E-02 ug/l 2.71E-04 lbs/day
Mirex 0.00E+00 ug/l 0.00E+00 lbs/day 1.0E-02 ug/l 9.03E-05 lbs/day
Parathion 1.30E-02 ug/l 7.59E-02 lbs/day 6.6E-02 ug/l 5.96E-04 lbs/day
PCB's 1.40E-02 ug/l 8.17E-02 lbs/day N/A ug/l #VALUE!lbs/day
Pentachlorophenol 1.50E+01 ug/l 8.76E+01 lbs/day 1.9E+01 ug/l 1.72E-01 lbs/day
Toxephene 2.00E-04 ug/l 1.17E-03 lbs/day 7.3E-01 ug/l 6.59E-03 lbs/day
Page 9
Utah Division of Water Quality
Salt Lake City, Utah
Effluent Limitations for Protection of Human Health [Toxics Rule]
Based upon Water Quality Standards (Most stringent of 1C or 3A & 3B as appropriate.)
In-stream criteria of downstream segments for Protection of Human Health [Toxics]
will be met with an effluent limit as follows:
Maximum Concentration
Concentration Load
Toxic Organics
Acenaphthene 2.32E+02 ug/l 1.35E+00 lbs/day
Acrolein 1.03E+03 ug/l 6.02E+00 lbs/day
Acrylonitrile 1.81E+01 ug/l 1.05E-01 lbs/day
Benzene 1.32E+02 ug/l 7.68E-01 lbs/day
Benzidine ug/l lbs/day
Carbon tetrachloride 1.29E+01 ug/l 7.53E-02 lbs/day
Chlorobenzene 2.06E+03 ug/l 1.20E+01 lbs/day
1,2,4-Trichlorobenzene
Hexachlorobenzene 2.04E-04 ug/l 1.19E-06 lbs/day
1,2-Dichloroethane 5.16E+03 ug/l 3.01E+01 lbs/day
1,1,1-Trichloroethane
Hexachloroethane 2.58E-01 ug/l 1.51E-03 lbs/day
1,1-Dichloroethane
1,1,2-Trichloroethane 2.30E+01 ug/l 1.34E-01 lbs/day
1,1,2,2-Tetrachloroethane 7.74E+00 ug/l 4.52E-02 lbs/day
Chloroethane
Bis(2-chloroethyl) ether 5.67E+00 ug/l 3.31E-02 lbs/day
2-Chloroethyl vinyl ether
2-Chloronaphthalene 2.58E+03 ug/l 1.51E+01 lbs/day
2,4,6-Trichlorophenol 7.22E+00 ug/l 4.21E-02 lbs/day
p-Chloro-m-cresol
Chloroform (HM)5.16E+03 ug/l 3.01E+01 lbs/day
2-Chlorophenol 2.06E+03 ug/l 1.20E+01 lbs/day
1,2-Dichlorobenzene 7.74E+03 ug/l 4.52E+01 lbs/day
1,3-Dichlorobenzene 2.58E+01 ug/l 1.51E-01 lbs/day
1,4-Dichlorobenzene 2.32E+03 ug/l 1.35E+01 lbs/day
3,3'-Dichlorobenzidine 3.87E-01 ug/l 2.26E-03 lbs/day
1,1-Dichloroethylene 5.16E+04 ug/l 3.01E+02 lbs/day
1,2-trans-Dichloroethylene1
2,4-Dichlorophenol 1.55E+02 ug/l 9.03E-01 lbs/day
1,2-Dichloropropane 7.99E+01 ug/l 4.67E-01 lbs/day
1,3-Dichloropropylene 4.38E+03 ug/l 2.56E+01 lbs/day
2,4-Dimethylphenol 7.74E+03 ug/l 4.52E+01 lbs/day
2,4-Dinitrotoluene 4.38E+00 ug/l 2.56E-02 lbs/day
2,6-Dinitrotoluene
1,2-Diphenylhydrazine 5.16E-01 ug/l 3.01E-03 lbs/day
Ethylbenzene 3.35E+02 ug/l 1.96E+00 lbs/day
Fluoranthene 5.16E+01 ug/l 3.01E-01 lbs/day
4-Chlorophenyl phenyl ether
4-Bromophenyl phenyl ether
Bis(2-chloroisopropyl) ether 1.68E+05 ug/l 9.78E+02 lbs/day
Bis(2-chloroethoxy) methane
Methylene chloride (HM)2.58E+03 ug/l 1.51E+01 lbs/day
Methyl chloride (HM)
Methyl bromide (HM)
Bromoform (HM)3.09E+02 ug/l 1.81E+00 lbs/day
Dichlorobromomethane(HM)6.96E+01 ug/l 4.06E-01 lbs/day
Chlorodibromomethane (HM)5.42E+01 ug/l 3.16E-01 lbs/day
Hexachlorocyclopentadiene 1.03E+01 ug/l 6.02E-02 lbs/day
Isophorone 4.64E+03 ug/l 2.71E+01 lbs/day
Naphthalene
Nitrobenzene 1.55E+03 ug/l 9.03E+00 lbs/day
2-Nitrophenol
4-Nitrophenol
2,4-Dinitrophenol 3.61E+04 ug/l 2.11E+02 lbs/day
4,6-Dinitro-o-cresol 1.97E+03 ug/l 1.15E+01 lbs/day
N-Nitrosodimethylamine 7.74E+00 ug/l 4.52E-02 lbs/day
N-Nitrosodiphenylamine 1.55E+01 ug/l 9.03E-02 lbs/day
N-Nitrosodi-n-propylamine 1.32E+00 ug/l 7.68E-03 lbs/day
Pentachlorophenol 1.03E-01 ug/l 6.02E-04 lbs/day
Phenol 7.74E+05 ug/l 4.52E+03 lbs/day
Bis(2-ethylhexyl)phthalate 9.54E-01 ug/l 5.57E-03 lbs/day
Butyl benzyl phthalate 2.58E-01 ug/l 1.51E-03 lbs/day
Page 10
Utah Division of Water Quality
Salt Lake City, Utah
Di-n-butyl phthalate 7.74E+01 ug/l 4.52E-01 lbs/day
Di-n-octyl phthlate
Diethyl phthalate 1.55E+03 ug/l 9.03E+00 lbs/day
Dimethyl phthlate 5.16E+03 ug/l 3.01E+01 lbs/day
Benzo(a)anthracene (PAH)3.35E-03 ug/l 1.96E-05 lbs/day
Benzo(a)pyrene (PAH)3.35E-04 ug/l 1.96E-06 lbs/day
Benzo(b)fluoranthene (PAH)3.35E-03 ug/l 1.96E-05 lbs/day
Benzo(k)fluoranthene (PAH)3.35E-02 ug/l 1.96E-04 lbs/day
Chrysene (PAH)3.35E-01 ug/l 1.96E-03 lbs/day
Acenaphthylene (PAH)
Anthracene (PAH)
Dibenzo(a,h)anthracene (PAH)3.35E-04 ug/l 1.96E-06 lbs/day
Indeno(1,2,3-cd)pyrene (PAH)3.35E-02 ug/l 1.96E-04 lbs/day
Pyrene (PAH)7.74E+01 ug/l 4.52E-01 lbs/day
Tetrachloroethylene 1.34E+03 ug/l 7.83E+00 lbs/day
Toluene 1.34E+03 ug/l 7.83E+00 lbs/day
Trichloroethylene 1.81E+01 ug/l 1.05E-01 lbs/day
Vinyl chloride 4.13E+00 ug/l 2.41E-02 lbs/day
Pesticides
Aldrin 1.99E-06 ug/l 1.16E-08 lbs/day
Dieldrin 3.09E-06 ug/l 1.81E-08 lbs/day
Chlordane 8.25E-04 ug/l 4.82E-06 lbs/day
4,4'-DDT 7.74E-05 ug/l 4.52E-07 lbs/day
4,4'-DDE 4.64E-05 ug/l 2.71E-07 lbs/day
4,4'-DDD 3.09E-04 ug/l 1.81E-06 lbs/day
alpha-Endosulfan 7.74E+01 ug/l 4.52E-01 lbs/day
beta-Endosulfan 1.03E+02 ug/l 6.02E-01 lbs/day
Endosulfan sulfate 1.03E+02 ug/l 6.02E-01 lbs/day
Endrin 7.74E-02 ug/l 4.52E-04 lbs/day
Endrin aldehyde 2.58E+00 ug/l 1.51E-02 lbs/day
Heptachlor 1.52E-05 ug/l 8.88E-08 lbs/day
Heptachlor epoxide
PCB's
PCB 1242 (Arochlor 1242)1.16E-04 ug/l 6.77E-07 lbs/day
PCB-1254 (Arochlor 1254)1.16E-04 ug/l 6.77E-07 lbs/day
PCB-1221 (Arochlor 1221)1.16E-04 ug/l 6.77E-07 lbs/day
PCB-1232 (Arochlor 1232)1.16E-04 ug/l 6.77E-07 lbs/day
PCB-1248 (Arochlor 1248)1.16E-04 ug/l 6.77E-07 lbs/day
PCB-1260 (Arochlor 1260)1.16E-04 ug/l 6.77E-07 lbs/day
PCB-1016 (Arochlor 1016)1.16E-04 ug/l 6.77E-07 lbs/day
Pesticide
Toxaphene 1.83E-03 ug/l 1.07E-05 lbs/day
Page 11
Utah Division of Water Quality
Salt Lake City, Utah
Metals
Antimony ug/l lbs/day
Arsenic ug/l lbs/day
Asbestos ug/l lbs/day
Beryllium
Cadmium
Chromium (III)
Chromium (VI)
Copper ug/l lbs/day
Cyanide ug/l lbs/day
Lead
Mercury ug/l lbs/day
Nickel ug/l lbs/day
Selenium
Silver
Thallium ug/l lbs/day
Zinc
Dioxin
Dioxin (2,3,7,8-TCDD)3.61E-08 ug/l 2.11E-10 lbs/day
Metals Effluent Limitations for Protection of All Beneficial Uses
Based upon Water Quality Standards and Toxics Rule
Class 4 Acute
Agricultural
Class 3 Acute
Aquatic
Wildlife
Acute Toxics
Drinking Water
Source
Acute Toxics
Wildlife
1C Acute
Health Criteria
Acute Most
Stringent
Class 3
Chronic
Aquatic
Wildlife
ug/l ug/l ug/l ug/l ug/l ug/l ug/l
Aluminum 1340.1 1340.1 N/A
Antimony 1650.4 1650.4
Arsenic 257.9 607.8 257.9 385.6
Barium
Beryllium 0.0
Cadmium 25.7 12.8 12.8 5.9
Chromium (III)9843.7 9843.7 676.8
Chromium (VI)256.6 25.5 25.49 22.09
Copper 514.5 89.8 89.8 75.8
Cyanide 39.4 1031.5 39.4 13.4
Iron 1788.4 1788.4
Lead 256.6 826.7 256.6 45.2
Mercury 4.29 0.39 0.39 0.031
Nickel 2656.9 11862.1 2656.9 424.6
Selenium 126.4 31.7 31.7 9.4
Silver 70.3 70.3
Thallium 1.2 1.2
Zinc 679.8 679.8 979.7
Boron 1934.0 1934.0
Sulfate 5157.4 5157.4
Page 12
Utah Division of Water Quality
Salt Lake City, Utah
Summary Effluent Limitations for Metals [Wasteload Allocation, TMDL]
[If Acute is more stringent than Chronic, then the Chronic takes on the Acute value.]
WLA Acute WLA Chronic
ug/l ug/l
Aluminum 1340.1 N/A
Antimony 1650.38
Arsenic 257.9 385.6 Acute Controls
Asbestos
Barium
Beryllium
Cadmium 12.8 5.9
Chromium (III)9843.7 677
Chromium (VI)25.5 22.1
Copper 89.8 75.8
Cyanide 39.4 13.4
Iron 1788.4
Lead 256.6 45.2
Mercury 0.387 0.031
Nickel 2656.9 425
Selenium 31.7 9.4
Silver 70.3 N/A
Thallium 1.2
Zinc 679.8 979.7 Acute Controls
Boron 1934.04
Sulfate 5157.4 N/A at this Waterbody
Other Effluent Limitations are based upon R317-1.
E. coli 126.0 organisms per 100 ml
X. Antidegradation Considerations
The Utah Antidegradation Policy allows for degradation of existing quality where it is determined
that such lowering of water quality is necessary to accommodate important economic or social
development in the area in which the waters are protected [R317-2-3]. It has been determined that
certain chemical parameters introduced by this discharge will cause an increase of the concentration of
said parameters in the receiving waters. Under no conditions will the increase in concentration be
allowed to interfere with existing instream water uses.
An Antidegradation Level I Review was conducted on this discharge and its effect on the
receiving water. Based upon that review, it has been determined that an
Antidegradation Level II Review is not required. The proposed permit is a simple renewal with no increase
in flow or concentration over that which was approved in the previous permit.
XI. Colorado River Salinity Forum Considerations
Discharges in the Colorado River Basin are required to have their discharge at a TDS loading
of less than 1.00 tons/day unless certain exemptions apply. Refer to the Forum's Guidelines
for additional information allowing for an exceedence of this value.
This doesn’t apply to facilities that do not discharge to the Colorado River Basin.
XII. Summary Comments
The mathematical modeling and best professional judgement indicate that violations of receiving
water beneficial uses with their associated water quality standards, including important down-
stream segments, will not occur for the evaluated parameters of concern as discussed above if the
effluent limitations indicated above are met.
Page 13