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species-specific response to temperature exposure. Information available from the scientific literature to provide <br /> general guidelines on the biological response for many of the species of organisms inhabiting the San Joaquin <br /> River,which have been used, in part, as the basis for this assessment(see Section 4.13.1, "Environmental <br /> Setting,"above). Information derived from analyses of the thermal characteristics of the discharge, in addition to <br /> information on the tidal currents and hydrodynamic patterns occurring within the lower San Joaquin River were <br /> also considered as part of this evaluation(see Appendix C, LWA 2007). <br /> Species of fish and macroinvertebrates,which inhabit the river and Delta year-round(i.e.,resident species), are <br /> characterized by a high tolerance to seasonal water temperature conditions(e.g.,these are generally referred to as <br /> warm-water species). Cold-water fish species, including Central valley fall-/late fall-run Chinook salmon and <br /> Central Valley steelhead are sensitive to exposure to elevated water temperatures during their juvenile and adult <br /> migration through the Delta and lower San Joaquin River. Given their sensitivity to seasonally elevated water <br /> temperatures,this assessment primarily focuses on fall-/late fall-run Chinook salmon and steelhead, although <br /> other species are also considered in the analysis. <br /> Because the habitat conditions within the portion of the lower San Joaquin River affected by the proposed City of <br /> Manteca WQCF discharge are not suitable for spawning and egg incubation by salmon or steelhead,the effects of <br /> water temperature on incubating eggs has not been included. Salmon and steelhead use the lower San Joaquin <br /> River as a migratory corridor, for both upstream migration by adults and downstream migration by juveniles, as <br /> well as a limited juvenile rearing and foraging. <br /> Based on the nature of thermal loading to the receiving water that occurs via the Manteca WQCF discharge outfall <br /> on the riverbank,three potential effects to fish and macroinvertebrates were assessed: <br /> 1. blockage or significant delay of upstream spawning migrations of adult anadromous fish,particularly <br /> anadromous salmonids, caused by the thermal plume that exists immediately downstream of the discharge <br /> outfall; <br /> 2. population-level effects resulting from potential mortality in fish or macroinvertebrates caused by acute <br /> (short-term) exposure to elevated water temperatures when moving past the discharge outfall; and <br /> 3. population or community-levels effects on fish and macroinvertebrates potentially resulting from the <br /> incremental increase in lower river/Delta water temperatures upon the Manteca WQCF effluent discharged <br /> becoming fully mixed with San Joaquin River water downstream of the outfall. <br /> The following assessment methodology was employed to address the thermal issues associated with the proposed <br /> project. <br /> Potential for Thermal Plume below the Discharge Outfall to Block or Delay the Upstream Spawning <br /> Migrations of Anadromous Fishes <br /> A three-dimensional,hydrodynamic RMA-10 model of the river in the vicinity of the WQCF discharge was used <br /> as the basis for the evaluation. Graphics and summary statistics data tables of the thermal plume below the <br /> discharge outfall were prepared from model simulations,under a variety of river and effluent flow and <br /> temperature combinations (see Appendix F). The graphics and summary data tables depict the thermal contours <br /> and attributes within the plume, for the initial(approximately)2,000 feet downstream of the discharge outfall, <br /> based on the simulated difference between river background temperature and effluent temperature and the flow <br /> rates for both the river and effluent. The contour graphics are color-coded so that the differential between effluent <br /> and river temperatures can be seen, in spatial context, downstream of the discharge outfall. Graphics showing a <br /> river plan view(from the discharge outfall to downstream 2,000 feet) and river cross-sectional views at 25 feet, <br /> 125 feet,250 feet,450 feet, 1,000 feet, and 2,000 feet downstream of the outfall were used for assessment <br /> purposes. These graphics were used, along with summary statistics data tables, for determining probabilities of <br /> temperature effects resulting from the proposed project, and characterizations of absolute temperatures that could <br /> Manteca WQCF and Collection System Master Plans EIR EDAW <br /> City of Manteca 4.13-17 Fisheries and Aquatic Resources <br />