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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2004-0028 -17- WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2004-0028 -18- CITY OF MANTECA,CITY OF LATHROP AND DUTRA FARMS CITY OF MANTECA,CITY OF LATHROP AND DUTRA FARMS WASTEWATER QUALITY CONTROL FACILITY WASTEWATER QUALITY CONTROL FACILITY SAN JOAQUIN COUNTY SAN JOAQUIN COUNTY mitigations,such as discharging during the outgoing tide,to bring the existing discharge into narrative toxicity objective by applying USEPA's Ambient Water Quality Criteria for the compliance and maintain compliance when increasing its effluent discharge rate. This Order Protection of Freshwater Aquatic Life for ammonia. This Order includes effluent limitations for may be reopened to include alternative limitations for temperature if a resolution is adopted in ammonia,based on the narrative toxicity objective and the USEPA's Ambient Water Quality the future that provides exceptions for particular objectives of the Thermal Plan. Criteria for the Protection of Freshwater Aquatic Life. 41. Studies by the National Marine Fisheries Service,the U.S.Fish and Wildlife Service,the Because of the seasonal variation in pH and temperature of the receiving water and the California Department of Fish and Game,the University of California at Davis,et.al.,have sensitivity of the ammonia criteria to these conditions,seasonal limitations are established. For identified the Central Valley Chinook Salmon and the Central Valley Steelhead as sensitive the warm weather months from 1 June to 30 September,the maximum permitted monthly species that are affected by elevated temperatures in the San Joaquin River. There are four runs average effluent pH is 8.0,the maximum historical monthly average receiving water pH is 9.1, of salmon in the Central Valley that results in there being adults and juveniles in portions of the the maximum historical monthly average effluent temperature is 27.2 F,and the maximum Delta every month of the year. Generally,adults would be moving upstream in the fall,and fry historical monthly average receiving water temperature is 25.7 F. The pH and temperature at the and smolt moving downstream in the winter and spring. River temperatures above 68 OF are edge of a 4:1 mixing zone were estimated utilizing the USEPA DESCON program. These unsuitable for supporting salmonids. Migration of adults is usually delayed when river estimations are utilized in Table 8 of the Information Sheet to calculate effluent limitations that temperatures reach this level. In a Department of Water Resources Study,adult salmon will maintain compliance with chronic aquatic criterion in the receiving water outside of the mixing cease migration if water temperatures are above 70 OF. At 77 OF,adult mortality may occur. zone. Effluent limitations compliant with acute criteria for conditions at the end-of-pipe are also The Thermal Plan does not protect aquatic life from high temperature wastewater being determined,but the more restrictive chronic criteria determine the final effluent limitations. discharged to an elevated temperature river. However,the Thermal Plan limits incremental Table 8 provides a daily maximum effluent limitation of 4.4 mg/l ammonia as N and a 30-day increases in temperature. Discharge from the wastewater treatment plant of treated effluent with average effluent limitation of 2.1 mg/l. As defined by the 1999 criteria,the 4-day average CCC an elevated temperature may affect salmon and other migrating fish in the San Joaquin River. In ammonia concentration shall not exceed 2.5 times the value of the 30-day CCC. However, so far as elevated temperature is deleterious to Chinook salmon,effluent temperature must be considering the maximum daily limitation is less than 2.5 times the CCC in all cases,the 4-day limited so as not to cause the receiving water to be harmful to the salmon. When the assimilative average cannot exceed the maximum daily limitation. capacity of the river is diminished,effluent temperature must be held to the water quality criteria. The CALFED Bay-Delta Program target is to maintain water temperatures below 68 OF For the cool weather months from 1 October to 31 May,the maximum permitted monthly in migratory routes of anadromous fish in the spring and fall. This Order requires the Discharger average effluent pH is 8.0,the maximum historical monthly average receiving water pH is 8.5, to study the potential impacts to the fishery associated with a discharge of effluent with elevated the maximum historical monthly average effluent temperature is 25.2 F,and the maximum temperature. historical monthly average receiving water temperature is 19.6 F. The pH and temperature at the edge of a 4:1 mixing zone were estimated utilizing the USEPA DESCON program. These 42. pH: The Discharger requested in a 17 October 2002 letter that the effluent pH range for estimations are utilized in Table 8 to calculate effluent limitations that maintain compliance with discharges to the San Joaquin River be restricted to pH 6.5 to 8.0. The reason for restricting the chronic aquatic criterion in the receiving water outside of the mixing zone. Effluent limitations pH of the discharge is to facilitate less restrictive ammonia effluent limitations for the discharge compliant with acute criteria for conditions at the end-of-pipe are also determined. In this case, to the San Joaquin River. These pH limits are included in this Order. the more restrictive acute criteria determine the final effluent limitations. Table 8 show that the acute criteria using the maximum permitted effluent pH of 8.0 provides a daily maximum 43. Ammonia-Nitrogen: Treated and untreated domestic wastewater,including the discharge from effluent limitation of 5.6 mg/1 ammonia as N and a 30-day average effluent limitation of the WQCF,contains ammonia. Nitrification is a biological process that converts ammonia to 2.8 mg/l. nitrite and nitrite to nitrate. Denitrification is a process that converts nitrate to nitrite or nitric oxide and then to nitrous oxide or nitrogen gas,which is then released to the atmosphere. 44. Nitrite and Nitrate-Nitrogen: Nitrate and nitrite are known to cause adverse health effects in Wastewater treatment plants commonly use nitrification to remove ammonia from the waste humans. The Basin Plan's chemical constituents water quality objective prohibits chemical stream. Inadequate or incomplete nitrification may result in the discharge of ammonia to the constituents in concentrations that exceed drinking water Maximum Contaminant Levels receiving stream. Ammonia is known to cause toxicity to aquatic organisms in surface waters. (MCLS)published in Title 22 of the California Code of Regulations or that adversely affect The USEPA has developed Ambient Water Quality Criteria for the Protection of Freshwater beneficial uses. Municipal and domestic water supply is a beneficial use of the San Joaquin Aquatic Life,recommending acute criteria for ammonia that are pH-dependent and chronic River. The California Department of Health Services(DHS)has adopted Primary Maximum criteria that are pH-and temperature-dependent. The WQCF effluent has a reasonable potential Contaminant Levels(MCLS)for the protection of human health for nitrite and nitrate that are to cause or contribute to an in-stream excursion above USEPA acute and chronic water quality equal to 1 mg/1 and 10 mg/1(measured as nitrogen),respectively. Title 22 CCR,Table 64431-A, criteria for ammonia. Consistent with 40 CFR section 122.44(d)(vi)(A)and the Basin Plan also includes a primary MCL of 10,000 ug/1 for the sum of nitrate and nitrite,measured as "Policy for Application of Water Quality Objectives",this Order implements the Basin Plan nitrogen. The discharge from the WQCF has a reasonable potential to cause or contribute to an