SITE INFORMATION AND CORRESPONDENCE_CASE 2

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CENTRAL VALLEY WATER BOA RESPONSE(SWRCB/OCC File A-1846, -7- PETITIONS FOR REVIEW OF W*rE DISCHARGE REQUIREMENTS ORDER NO. R5-2007-0036 (NPDES NO. CA0079154)AND TIME SCHEDULE ORDER NO. R5-2007-0037 CITY OF TRACY, WASTEWATER TREATMENT PLANT nitrate and/or nitrite to the receiving stream. The applicable objectives are maximum contaminant levels incorporated in the chemical constituents objectives. (See, Fact Sheet, pp. F-37-38.) Acute Toxicity. The Basin Plan states that "...effluent limits based upon acute biotoxicity tests of effluents will be prescribed where appropriate..." (Basin Plan pg. III-9.00) The Facility receives waste from industrial users, which can discharge toxic pollutants to the Facility, therefore, it is appropriate to require effluent limitations for acute toxicity in accordance with the Basin Plan. Chlorine Residual. The Discharger uses chlorine for disinfection, which is extremely toxic to aquatic organisms. The Discharger uses a sulfur dioxide process to dechlorinate the effluent prior to discharge to Old River. Due to the existing chlorine use and the potential for chlorine to be discharged, the discharge has a reasonable potential to cause or contribute to an in-stream excursion above the Basin Plan's narrative toxicity objective. The effluent limits for chlorine residual were established based on USEPA's 1984 Ambient Water Quality Criteria for Chlorine. Mercury. Fish tissue monitoring has been conducted in Old River in the vicinity of the discharge 2. Based on eight fish tissue monitoring samples of legally catchable largemouth bass collected from 1998-1999 in Old River near Paradise Cut, mercury fish tissue concentrations ranged from 0.20 mg/kg to 0.58 mg/kg, with an average of 0.39 mg/kg. These fish tissue monitoring data include exceedances of the USEPA recommended mercury criterion for the protection of human health, 0.3 mg/kg in fish tissue, thus demonstrating a lack of assimilative capacity for mercury in Old River. (See, Fact Sheet, pp. F-11 and F-36.) Since mercury is contained in the discharge, there is reasonable potential for the discharge to cause, or contribute to an in-stream excursion of the Basin Plan's narrative toxicity objective, based on the USEPA's recommended fish tissue criterion for the protection of human health. The Discharger argues that narrative effluent limitations are invalid because USEPA intended them to be temporary. Nothing in the regulations allows a state to avoid enforcing narrative objectives. (40 CFR § 122.44(d)(v) and (vi).) These regulations require acute and chronic toxicity limitations unless the permitting authority demonstrates that pollutant- specific limitations are sufficient to attain numeric and narrative standards, and, unless infeasible, require pollutant-specific limitations using a calculated numeric criterion that will attain the narrative criteria; establish case-by-case limitations based on EPA criteria; or establish limitations for indicator parameters. (40 CFR § 122.44(d)(vi)(A) —(C).) The Basin Plan's narrative objectives and Policy for Application of Water Quality Objectives include s Sampling performed by San Francisco Estuary Institute (see Attachment 1). This data represents fish tissue sampling of trophic level 4 largemouth bass that are of size to be consumed by humans (length greater than legal size limit).