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anadromous fishes past the Manteca WQCF discharge outfall,thereby resulting in adverse population-level <br /> effects; and <br /> ► cause sufficient degradation in water quality immediately downstream of the Manteca WQCF discharge <br /> outfall that would result in a substantial potential for lethality to organisms passing through the zone of initial <br /> mixing. <br /> Findings from these impact assessments were compared to these significance criteria to make impact <br /> determinations. <br /> IMPACT ANALYSIS <br /> Temperature <br /> Preparation of the 2000 Draft EIR for the Manteca WQCF Phase III/IV Expansion Project(EDAW 2000) <br /> revealed that the WQCF effluent would not comply with all objectives of the"Water Quality Control Plan for <br /> Control of Temperature in the Coastal and Interstate Waters and Enclosed Bays and Estuaries of California" <br /> (Thermal Plan; SWRCB 1972)under some conditions. Because the WQCF outfall is an existing discharge in the <br /> tidally influenced reach of the San Joaquin River, Section 5.A of the Thermal Plan applies to the discharge and <br /> stipulates the following: <br /> 1. Elevated temperature waste discharges shall comply with the following: <br /> a. The maximum temperature shall not exceed the natural receiving water temperature by more than 20°F. <br /> b. Elevated temperature waste discharges either individually or combined with other discharges shall not <br /> create a zone, defined by water temperatures of more than 1°F above natural receiving water temperature, <br /> which exceeds 25%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 above the natural temperature <br /> of the receiving waters at any time or place. <br /> In general,the current permitted WQCF effluent is warmer than the San Joaquin River, and if evaluated on a <br /> monthly average,objective a. of the Thermal Plan is met for the WQCF discharge. Because the effluent is warmer <br /> than the receiving water,objectives b. and c. of the Thermal Plan are not necessarily met within the WQCF <br /> plume. By operating under a timed discharge during periods of low river flow to discharge only on the outgoing <br /> tide,the thermal plume will meet objective b. of the Thermal Plan. However,the temperature difference between <br /> the discharge and the river may exceed objective c. of the Thermal Plan. Pursuant to General Water Quality <br /> Provision 4 of the Thermal Plan,the City of Manteca is pursuing a limited exception to specific Thermal Plan <br /> water quality objectives for the permitted discharge rate of 9.87 MGD (LWA 2006). The current thermal analysis <br /> is expanded to evaluate the thermal effects of 27 mgd WQCF discharges on the San Joaquin River(full build-out). <br /> As stated in the Impact Assessment Methodology section(above),the current Thermal Plan and NPDES permit <br /> limitations are not well supported by the current science regarding thermal effects on aquatic life. Therefore, <br /> compliance with these temperature limitations is not predictive of(or well correlated to)thermal impacts to <br /> aquatic life downstream of the Manteca WQCF discharge. Consequently, a detailed, scientifically based, <br /> quantitative assessment of near-field and fully mixed temperature modeling results for the purposes of assessing <br /> potential thermal impacts of the project to aquatic life is provided below. <br /> EDAW Manteca WQCF and Collection System Master Plans EIR <br /> Fisheries and Aquatic Resources 4.13-20 City of Manteca <br />