ARCHIVED REPORTS_DRAFT ENVIRONMENTAL IMPACT REPORT

Home Browse Search

comply with all California Thermal Plan Objectives,which have been established to be protective of beneficial uses. The reduction in temperature of the treated effluent will prevent the creation of a lethal zone or plume, defined as water temperatures that are at or above the lethal effects levels(i.e.,>68°F) during time periods when the most sensitive fish species would be in the vicinity of the WQCF outfall(i.e., from January to May)and ambient background temperatures are at or below these lethal effects levels. Because the ambient water temperature of the San Joaquin River can exceed the>68°F lethal effects threshold during the later portion of the time period when sensitive species are present(e.g.,April and May),the temperature of the treated effluent produced by the cooling tower or equivalent technology may be greater than ambient background river temperatures under these conditions and during these periods. This could result in conditions where the plume exceeds the lethal effects threshold; however,with implementation of the cooling tower or equivalent technology, the size and intensity of the plume will be minimized resulting in only short-term exposure (through reduced plume size)to marginally increased water temperatures. Because sensitive fish species have been documented (Moyle 2002,Bartholow and Henricksen 2004,Bjorn and Reiser 1991)to survive exposure to higher temperatures(beyond lethal effects thresholds)for short periods of time, substantial adverse impacts to fish would not occur. Furthermore,the cooling tower or equivalent technology will be designed to cool treated effluent to meet all California Thermal Plan objectives that were established, in part,to be protective of beneficial uses including cold water fish habitat. The cooling tower or equivalent technology cooling capacity of 15°F would achieve an effluent temperature within 3°F to 4°F of the ambient river temperature. Before the design of the cooling tower or equivalent technology is finalized,the City of Manteca will obtain the approval of the RWQCB indicating that the cooling tower or equivalent technology design is adequate to address concerns regarding discharge of higher temperature treated effluent into the San Joaquin River. The cooling tower or equivalent technology will be constructed, installed,and operated in accordance with the approved final design prior to operating the WQCF at the expanded capacity(i.e.,greater than 9.87 mgd ADWF). Implementation of a cooling tower or equivalent technology would reduce impacts to fisheries resources that may otherwise result from the increased discharge of higher temperature treated effluent into the San Joaquin River to a less-than-significant level. The specific design, siting, and operational characteristics of the cooling tower or equivalent technology are unknown at this time. Construction and operation of the cooling tower or equivalent technology could potentially result in many of the same significant environmental impacts as the project(e.g., agricultural resources, construction-related air quality,noise,geology and soils, cultural resources), some of which may remain significant and unavoidable with implementation of all feasible mitigation. In particular, construction of the cooling tower or equivalent technology has the potential to result in significant and unavoidable impacts on farmland. 4.13.4 LEVEL OF SIGNIFICANCE AFTER MITIGATION With implementation of the mitigation measure identified above,the project's fisheries and aquatic resources impacts would be reduced to a less-than-significant level because the design, installation, and operation of a cooling tower or equivalent technology would ensure that treated effluent discharged into the San Joaquin River would be reduced by up to 15°F, and the effluent discharge and associated size and intensity of the thermal plume will not result in adverse thermal affects to the health and/or condition of sensitive fish species. Construction and operation of the cooling tower or equivalent technology could result in significant and unavoidable impacts on farmland even with implementation of all feasible mitigation.No other feasible mitigation could be implemented by the project to reduce these impacts. Therefore, farmland impacts would remain significant and unavoidable. Manteca WQCF and Collection System Master Plans EIR EDAW City of Manteca 4.13-27 Fisheries and Aquatic Resources