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Home My WebLink AboutDWQ-2025-004506 Page 1 of 4 Utah Division of Water Quality Statement of Basis ADDENDUM Wasteload Analysis and Antidegradation Level I Review Date: May 19, 2025 Prepared by: Suzan Tahir Standards and Technical Services Facility: Ferron Wastewater Treatment Facility Castle Valley Special Service District UPDES No. UT0020052 Receiving water: Ferron 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: Ferron Creek The maximum daily design discharge is 0.5 MGD and the maximum monthly design discharge is 0.5 MGD for the facility. Receiving Water The receiving water for Outfall 001 is Ferron Creek, which is tributary to the San Rafael River, which drains to the Colorado River. Per UAC R317-2-13.1(b), the designated beneficial uses for Ferron Creek and tributaries, from confluence with San Rafael River to Millsite Reservoir 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. Utah Division of Water Quality Wasteload Analysis Ferron Wastewater Treatment Plant UPDES No. UT0020052 Page 2 of 4  Class 4 - Protected for agricultural uses including irrigation of crops and stock watering. 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 limited of flow records for Ferron Creek for the period 2015-2025, the 20th percentile of flow measurements at 4930798 Ferron Ck ab New Ferron Lagoons 001 was used to calculate annual critical low flow in the receiving water (Table 1). Table 1: Annual critical low flow for Ferron Creek above New Ferron lagoon outfall Season Count Flow (cfs) Annual 8 1.88 Receiving water quality Receiving water quality data were obtained from monitoring sites 4930820 Ferron Creek above Ferron Lagoons 001 at U10 Crossing and 4930798 Ferron Creek above New Ferron Lagoons 001. 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 4930796 Ferron Lagoons New 001. Mixing Zone The maximum allowable mixing zone is 15 minutes of travel time for acute conditions, not to exceed 50% of stream width, and 2,500 feet for chronic conditions, per UAC R317-2-5. Water quality standards must be met at the end of the mixing zone. The actual length of the mixing zone was not determined; however, it was presumed to remain within the maximum allowable mixing zone dimensions. Acute limits were calculated using 50% of the seasonal critical low flow. Parameters of Concern The potential parameters of concern identified for the discharge/receiving water were total suspended solids (TSS), dissolved oxygen (DO), BOD5, total phosphorus (TP), total nitrogen (TN), total ammonia (TAN), E. coli, pH, and total residual chlorine (TRC) as determined in consultation with the UPDES Permit Writer. Utah Division of Water Quality Wasteload Analysis Ferron Wastewater Treatment Plant UPDES No. UT0020052 Page 3 of 4 TMDL According to the 303(d) list in Utah’s 2024 Integrated Report, the receiving water body for the discharge, Ferron Creek Lower (Ferron Creek and tributaries from confluence with San Rafael River to Millsite Reservoir, UT14060009-012_00 supports all designated uses. Per UAC R317-2-14, Ferron Creek 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 29% Effluent Limits Effluent limits were determined using a mass balance mixing analysis (UDWQ 2012). The mass balance analysis is summarized in Appendix A. The water quality standard for chronic ammonia toxicity is dependent on temperature and pH, and the water quality standard for acute ammonia toxicity is dependent on pH. The seasonal average temperature and pH of Ferron Creek from the previous wasteload analysis were used to determine the chronic criteria, and the seasonal 80th percentile pH was used to determine the acute criteria. The water quality standards for ammonia are summarized in Appendix A. The limits for total residual chlorine were determined assuming a decay rate of 20 /day (at 20 ºC) and a travel time in the outlet ditch of 10 minutes (1,000 linear feet at 0.02 ft/ft slope) prior to discharge to Ferron Creek. The analysis for TRC is summarized in Appendix C. Due to the lack of discharge since 2005, the effects of TP, TN, DO and BOD5 in the effluent on the DO in the downstream receiving waters was not assessed. It is presumed that previous permit limits for these constituents, if applicable, would be sufficiently protective of the receiving water. Utah Division of Water Quality Wasteload Analysis Ferron Wastewater Treatment Plant UPDES No. UT0020052 Page 4 of 4 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 Review II 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. Documents: WLA Document: ferron_potw_wla_2025.docx Wasteload Analysis: ferron_potw_wla_2025.xlsm 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. 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 WASTELOAD ANALYSIS [WLA]Date:5/19/2025 Appendix A: Mass Balance Mixing Analysis for Conservative Constituents Discharging Facility:Ferron Lagoons UPDES No:UT-0020052 Permit Flow [MGD]:0.50 Annual Max. Daily 0.50 Annual Max. Monthly Receiving Water:Ferron Creek Stream Classification:2B, 3C, 4 Stream Flows [cfs]:1.9 All Seasons Critical Low Flow 20th % Fully Mixed:NO Acute River Width:50% Chronic River Width:100% Modeling Information A simple mixing analysis was used to determine the effluent limits. All model numerical inputs, intermediate calculations, outputs and graphs are available for discussion, inspection and copy at the Division of Water Quality. 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 reflect the environmental conditions expected at low stream flows. Effluent Limitations for Protection of Recreation (Class 2B Waters) Physical Parameter Maximum Concentration pH Minimum 6.5 pH Maximum 9.0 Turbidity Increase (NTU)10.0 Bacteriological E. coli (30 Day Geometric Mean)206 (#/100 mL) E. coli (Maximum)668 (#/100 mL) Page A-1 Utah Division of Water Quality Effluent Limitations for Protection of Aquatic Wildlife (Assumed Class 3C Waters) Temperature (deg C)Maximum Instantaneous 27.0 Change 4.0 Dissolved Oxygen (mg/L)Minimum Concentration Instantaneous 3.0 30-day Average 5.0 pH Concentration Minimum 6.5 Maximum 9.0 Inorganics Chronic Standard (4 Day Average)Acute Standard (1 Hour Average) Parameter Standard Standard Phenol (mg/L)0.010 Hydrogen Sulfide (Undissociated) [mg/L]0.002 Ammonia-Total (mg/L) Chronic (30-day ave)Acute (1-hour ave) Season Standard Background Limit Standard Background Limit Summer 2.3 0.030 7.8 9.6 0.030 21.2 Fall 4.4 0.030 15.0 9.2 0.030 20.4 Winter 5.6 0.030 19.1 9.4 0.030 20.8 Spring 2.0 0.030 6.6 4.0 0.030 8.9 Metals-Total Recoverable Chronic (4-day ave)Acute (1-hour ave) Parameter Standard1 Background Limit Standard1 Background Limit Aluminum (µg/L)87.0 21.0 247.4 750.0 21.0 1635.9 Arsenic (µg/L)150.0 2.7 508.0 340.0 2.7 749.9 Cadmium (µg/L)0.6 0.48 1.1 7.7 0.48 16.6 Chromium VI (µg/L)11.0 5.4 24.6 16.0 5.4 28.9 Chromium III (µg/L)230.7 5.4 778.2 1773.3 5.4 3921.7 Copper (µg/L)29.3 6.2 85.4 49.6 6.2 102.4 Cyanide (µg/L)2 5.2 3.5 9.4 22.0 3.5 44.5 Iron (µg/L)1000.0 23.0 2187.3 Lead (µg/L)10.9 1.3 34.4 280.8 1.3 620.6 Mercury (µg/L)2 0.012 0.008 0.022 2.4 0.008 5.3 Nickel (µg/L)168.0 5.8 562.4 1512.9 5.8 3344.4 Selenium (µg/L)4.6 2.1 10.7 18.4 2.1 38.2 Silver (µg/L)34.9 1.1 76.0 Tributylin (µg/L)2 0.072 0.048 0.130 0.46 0.048 0.96 Zinc (µg/L)382.4 24.0 1253.5 379.3 24.0 811.1 1: Based upon a Hardness of 400 mg/l as CaCO3 2: Background concentration assumed 67% of chronic standard Page A-2 Utah Division of Water Quality Organics [Pesticides] Chronic (4-day ave)Acute (1-hour ave) Parameter Standard Limit Standard Limit Aldrin (µg/L)1.5 1.5 Chlordane (µg/L)0.0043 0.0043 1.2 1.2 DDT, DDE (µg/L)0.001 0.001 0.55 0.55 Diazinon (µg/L)0.17 0.17 0.17 0.17 Dieldrin (µg/L)0.0056 0.0056 0.24 0.24 Endosulfan, a & b (µg/L)0.056 0.056 0.11 0.11 Endrin (µg/L)0.036 0.036 0.086 0.086 Heptachlor & H. epoxide (µg/L)0.0038 0.0038 0.26 0.26 Lindane (µg/L)0.08 0.08 1.0 1.0 Methoxychlor (µg/L)0.03 0.03 Mirex (µg/L)0.001 0.001 Nonylphenol (µg/L)6.6 6.6 28.0 28.0 Parathion (µg/L)0.0130 0.0130 0.066 0.066 PCB's (µg/L)0.014 0.014 Pentachlorophenol (µg/L)15.0 15.0 19.0 19.0 Toxephene (µg/L)0.0002 0.0002 0.73 0.73 Radiological Maximum Concentration Parameter Standard Gross Alpha (pCi/L)15 Effluent Limitation for Protection of Agriculture (Class 4 Waters) Maximum Concentration Parameter Standard Background Limit Total Dissolved Solids (mg/L)3500 3500 Boron (mg/L)0.75 0.8 Arsenic, Dissolved (µg/L)100 100 Cadmium, Dissolved (µg/L)10 10.0 Chromium, Dissolved (µg/L)100 100 Copper, Dissolved (µg/L)200 200 Lead, Dissolved (µg/L)100 100 Selenium, Dissolved (µg/L)50 50 Gross Alpha (pCi/L)15 15.0 Page A-3 Utah Division of Water Quality WASTELOAD ANALYSIS [WLA]Date:5/19/2025 Appendix C: Total Residual Chlorine Discharging Facility:Ferron Lagoons UPDES No:UT-0020052 CHRONIC Decay Rate (/day) Season Receiving Water Standard Total Effluent Mixing Zone Boundary Effluent Limit Without Decay Temperature (°C) @ 20 deg C @ T deg C Travel Time (min) Decay Coefficient Effluent Limit Discharge (cfs)Annual 1.9 0.8 2.7 TRC (mg/L)Annual 0.000 0.011 0.038 20.0 20 20.0 10 0.87 0.043 ACUTE Decay Rate (/day) Season Receiving Water Standard Total Effluent Mixing Zone Boundary Effluent Limit Without Decay Temperature (°C)@ 20 °C @ T °C Travel Time (min) Decay Coefficient Effluent Limit Discharge (cfs)Annual 0.9 0.8 1.7 TRC (mg/L)Annual 0.000 0.019 0.042 20.0 20 20.0 10 0.87 0.048 Page C-1