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REGIONAL WATER BOARD RESPONSE (SWRCB/OCC File A-1846(a) and A-1846(b)) _16- <br /> PETITIONS FOR REVIEW OF V E DISCHARGE REQUIREMENTS <br /> ORDER NO. R5-2007-0036 (NPDCO NO. CA0079154) AND <br /> TIME SCHEDULE ORDER NO. R5-2007-0037 <br /> CITY OF TRACY, WASTEWATER TREATMENT PLANT <br /> CSPA — CONTENTION G: Temperature limitations violate the Basin Plan, Thermal Plan <br /> and federal regulations. Unless the Order is allowing a mixing zone, compliance with the <br /> effluent limitation would cause immediate violation of the Receiving Water Limitations. The <br /> receiving water limitations are apparently based on Basin Plan water quality objectives, <br /> whereas the Effluent Limitation appears-to_hatye no technical or legal explanation. <br /> CSPA contends that the temperature limitations violate the Basin Plan, Thermal Plan and <br /> federal regulations. Regional Water Board staff disagree with this contention. The <br /> temperature effluent limitations and receiving water limitations in Order R5-2007-0036 are <br /> applied based on the Thermal Plan's water quality objectives for temperature. <br /> The State Water Board adopted a Water Quality Control Plan for Control of Temperature in <br /> the Coastal and Interstate Waters and Enclosed Bays and Estuaries of California (Thermal <br /> Plan) on 18 May 1972, and amended this plan on 18 September 1975. This plan contains <br /> temperature objectives for inland surface waters. The Thermal Plan is applicable to the <br /> discharge. For purposes of the Thermal Plan, the Discharger is considered to be an Existing <br /> Discharger of Elevated Temperature Waste. The Thermal Plan in section 5.A. requires the <br /> following: <br /> "5. Estuaries <br /> A. Existing discharges <br /> (1) Elevated temperature waste discharges shall comply with the following: <br /> a. The maximum temperature shall not exceed the natural receiving water <br /> temperature by more than 20°F. <br /> b. Elevated temperature waste discharges either individually or combined with <br /> other discharges shall not create a zone, defined by water temperatures of <br /> more than 1 OF above natural receiving water temperature, which exceeds <br /> 25 percent of the cross-sectional area of a main river channel at any point. <br /> c. No discharge shall cause a surface water temperature rise greater than 4°F <br /> above the natural temperature of the receiving waters at any time or place. <br /> d. Additional limitations shall be imposed when necessary to assure protection <br /> of beneficial uses. <br /> (2) Thermal waste discharges shall comply with the provisions of 5A (1) above <br /> and, in addition, the maximum temperature of thermal waste discharges shall <br /> not exceed 86°F." <br /> The Order includes effluent limitations in accordance with 5.A.(1)a of the Thermal Plan and <br /> receiving water limits in accordance with 5.A.(1)b and 5.A.(1)c. The Discharger currently <br /> complies with the Thermal Plan requirements at the existing flow rate of 9 mgd. However, <br /> modeling by the Discharger indicates that the 1°F limitation of Objective 5.A.(1)b of the <br /> Thermal Plan may be exceeded 3 months of the year at the expanded discharge flow rate of <br /> 16 mgd. As described in the Final Environmental Impact Report (EIR) for the expansion of the <br />