SITE INFORMATION AND CORRESPONDENCE 1980-1999

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r r WASTE DISCHARGE REQUIREMENTS ORDER NO. 2000-**** -6- -6- CITY OF LODI WHITE SLOUGH WATER POLLUTION CONTROL PLANT SAN JOAQUIN COUNTY interim, the Discharger is required to develop a program for identification and control of mercury discharged within the collection system. 26. EPA's ambient water quality criteria for protection of aquatic life for a continuous concentration of lead is 3.6 µg/1 (30-day average, chronic criteria), based on a water hardness of 110 mg/l, and as converted to be expressed as total recoverable metal. Effluent monitoring for lead has shown the median concentration to be 1.5 µg/1, and the highest measured to be 10 gg/1, with 3 of 18 samples exceeding the converted chronic criteria. Five of the 18 samples had a relatively high reporting/detection limit of 5.0 µg/1. A thirty-day average effluent limitation for lead is included in this Order, based on the converted chronic criteria. The Discharger is not currently capable of meeting this limit with the current treatment facilities. 27. Based on information submitted as part of the application, in studies, and as directed by monitoring and reporting programs, the Board finds that the discharge has a reasonable potential to cause or contribute to a violation of the Basin Plan narrative prohibition against the discharge of toxic substances in toxic concentrations with respect to chlorine. USEPA developed Ambient Water Quality Criteria for the Protection of Aquatic Life (Criteria) as recommended concentrations to protect against aquatic toxicity. This Order, and the Basin Plan, prohibits the discharge of toxic constituents in toxic amounts. Chlorine is used as*a disinfectant at the wastewater treatment plant and, based on experience, has a reasonable potential to be discharged in toxic concentrations. The Criteria are well established and have undergone extensive testing and peer review. The Criteria are an appropriate measure of toxicity, and are the basis for establishing effluent limitations for chlorine. Because there is no significant dilution within Dredger Cut in the immediate vicinity of the discharge over the averaging period for acute toxicity water quality objectives, no mixing zone is designated for chlorine. 28. The Sacramento-San Joaquin Delta has been listed as an impaired waterbody pursuant to Section 303(d) of the Clean Water Act because of: (1) diazinon and chlorpyrifos (organophoshate pesticides), (2) aldrin, dieldrin, chlordane, endrin, heptachlor, heptachlor epoxide, hexachlorocyclohexane (including lindane), endosulfan and toxaphene (chlorinated hydrocarbon pesticides), (3)DDT, and (4) unknown toxicity. The Basin Plan requires that; no individual pesticides shall be present in concentrations that adversely affect beneficial uses; discharges shall not result in pesticide concentrations in bottom sediments or aquatic life that adversely affects beneficial uses; total chlorinated hydrocarbon pesticide concentrations shall not be present in the water column at detectable concentrations and pesticide concentrations shall not exceed those allowable by applicable anti degradation policies. The Basin Plan's requirement that persistent chlorinated hydrocarbon pesticides shall not be present in the water column in detectable concentrations is the most stringent criteria for the regulation of the detected persistent organochlorine pesticides. The Discharger has not previously been required to complete effluent analyses for diazinon or chlorpyrifos. Analytical results of monitoring for pesticides on the 303(d) listing other than diazinon or chlorpyrifos are summarized in the attached Fact Sheet (Attachment C). The analytical results indicate that lindane (an organochlorine pesticide) was detected in 7 of 19