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INFORMATION SHEET 0 . 5 WASTE DISCHARGE REQUIRMENTS ORDER NO. R5-2003-XXXX SPX CORPORATION MARLEY COOLING TOWER COMPANY STOCKTON, SAN JOAQUIN COUNTY is lost by evaporation, flow downstream and percolation to groundwater providing a source of municipal and irrigation water supply. d. Freshwater Replenishment There are periods of hydraulic continuity between the Stockton Diverting Canal and the Calaveras River. During periods of hydraulic continuity, the Stockton Diverting Canal contributes some or all of the water quantity and may impact the quality of water flowing down stream in the Calaveras River. e. Preservation and Enhancement offish, Wildlife and Other Aquatic Resources. The Basin Plan (Table 1I-1) designates the Calaveras River as being a cold freshwater habitat. The Stockton Diverting Canal exchanges water with the Calaveras River, diverting water from Morman Slough, which originates from the Calaveras River, back into the Calaveras River. There is aquatic habitat in the Stockton Diverting Canal and hydraulic continuity between the Canal and Calaveras River from the point of discharger from Outfall 001 to where the Canal discharges into the Calaveras River. Pursuant to the tributary rule and Basin Plan (Table H-1, Footnote(2)), and the presence of cold water aquatic habitat in the Stockton Diverting Canal, the cold designation is applicable to the Stockton Diverting Canal. The cold-water habitat designation necessitates that the in- stream dissolved oxygen concentration be maintained at, or above, 7.0 mg/L(ppm). This approach recognizes that, if the naturally occurring in-stream dissolved oxygen concentration is below 7.0 mg/L(ppm), the Discharger is not required to improve the naturally occurring level. Upon review of the flow conditions, habitat values, existing and potential beneficial uses of the Calaveras River, and the facts described above, the Regional Board finds that the benficial uses identified in the Basin Plan for the Calaveras River are applicable to the Stockton Diverting Canal. The Regional Board also finds that based on the available information and on the Discharger's application, that the Stockton Diverting Canal, absent the discharge, is at times a seasonal and/or ephemeral waterbody. This seasonal and/or ephemeral nature of the Stockton Diverting Canal means that the designated beneficial uses must be protected,but that no year-round credit for receiving water dilution is available. Although the discharge, at times, maintains the aquatic habitat, constituents may not be discharged that may cause harm to aquatic life. At other times, flows within the Stockton Diverting Canal help support the cold-water aquatic life. Both conditions may exist within a short time span, where the Stockton Diverting Canal would be dry without the discharge and periods when sufficient background flows provide hydraulic continuity with the Calaveras River. The lack of dilution results in more stringent effluent limitations to protect contact recreational uses, drinking water standards, agricultural water quality goals and