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occur within the plume,to determine whether the thermal characteristics of the plume pose a potential to block or <br /> significantly delay upstream spawning migrations of anadromous fishes. The scientific basis for making the <br /> blockage delay determination considered: <br /> 1. the presence of a sufficient portion of the river,in the area of the plume and downstream,that remains <br /> thermally unaffected or negligibly affected,thereby providing a"zone of passage;" <br /> 2. location in the water column and river cross-section that fish species evaluated typically move; <br /> 3. behavioral responses of immigrating adult anadromous fish when they encounter thermal plumes; <br /> 4. the time of year that the species assessed immigrate past the discharge outfall; <br /> 5. the threshold temperature range for blockage of salmonid passage(i.e., avoidance temperatures); and <br /> 6. the thermal tolerances of adult anadromous fishes that pass the discharge outfall on their migrations through <br /> the lower San Joaquin River to upstream spawning grounds. <br /> Potential for the Thermal Plume to Adversely Affect Fish or Macroinvertebrates Passing the Discharge <br /> Outfall <br /> The same model output graphics and summary statistics discussed above(see Appendix F)were used to assess <br /> whether mortality(acute direct or delayed, indirect mortality)would be expected to occur in fish and <br /> macroinvertebrates that actively move or drift downstream through the zone of initial effluent mixing, <br /> downstream of the discharge outfall. These graphics and summary statistics tables were used for river background <br /> and effluent absolute temperatures and absolute temperatures that could occur within the plume,to determine <br /> whether the thermal characteristics of the plume could cause a thermal shock to biota of sufficient magnitude and <br /> frequency to cause acute direct mortality or delayed, indirect mortality,thereby resulting in adverse population-or <br /> community-level effects. The scientific basis for making this determination considered: <br /> 1. the seasonal and condition-specific cross-sectional thermal characteristics of the river, downstream of the <br /> discharge outfall; <br /> 2. location in the water column that various aquatic species typically move,when passing the discharge outfall; <br /> 3. the time of year that various aquatic species move downstream past the discharge outfall; <br /> 4. behavioral responses of the biota evaluated when encountering thermal plumes; <br /> 5. thermal tolerances of a representative number of biota known to move past the discharge outfall during one or <br /> more periods of their life cycle; and <br /> 6. swimming speeds of actively swimming fishes (i.e.,the length of time aquatic species would be subjected to <br /> the thermal plume). <br /> Population- or Community-level Effects to Fish or Macroinvertebrates from the Incremental Increase in <br /> Downstream Water Temperatures <br /> The fraction or percentage of WQCF effluent present at various downstream locations within the Delta was <br /> modeled in order to provide an indication of the far-field impacts of the proposed project on Delta water quality. <br /> Six locations within the Delta(see Exhibit 4.9-2)were chosen as far-field sites for the evaluation of water quality <br /> impacts due to increased WQCF discharge. Sites were selected to provide pre-and post-project water quality <br /> estimates at several drinking water export locations and the Stockton Deep Water Ship Channel(DWSC). The <br /> EDAW Manteca WQCF and Collection System Master Plans EIR <br /> Fisheries and Aquatic Resources 4.13-18 City of Manteca <br />