SITE INFORMATION AND CORRESPONDENCE_1993-2003

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INFORMATION SHEET • • 7 WASTE DISCHARGE REQUIRMENTS ORDER NO. 115-2002-0213 U.S. DEPARTMENT OF DEFENSE DEFENSE LOGISTICS AGENCY DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN SHARPE GROUNDWATER REMEDIATION SYSTEM SAN JOAQUIN COUNTY c. Groundwater Recharge In areas or at times when groundwater elevations are below the French Camp Slough bottom,water from the Slough will percolate to groundwater. Since flow in the SSJID Canal and French Camp Slough is at times minimal, it is reasonable to assume that the stream water originating from the SSJID Canal is lost by evaporation, flow downstream and percolation to groundwater providing a source of municipal and irrigation water supply. d. Freshwater Replenishment French camp Slough is in hydraulic continuity with the Delta, and flow is influenced by tidal conditions in the Delta. The water quanlity of French Camp Slough affects the quality of water in the Delta. e. Preservation and Enhancement offish, Wildlife and Other Aquatic Resources. French Camp Slough flows to the Delta. Studies have suggested that French Camp Slough provides up to 5% of the flow to the San Joaquin River when the river flow is near 1000 cubic feet per second(cfs), though it could be up to 30% or more when the river flow drops to 150 cfs. Fish species present in French Camp Slough and the Delta are consistent with both cold and warm water fisheries. There are no significant barriers to aquatic organism movement or migration from the San Joaquin River and Delta to French Camp Slough. The Basin Plan (Table H-1) designates the Delta as being both a cold and warm freshwater habitat. Therefore,pursuant to the Basin Plan (Table II-1, Footnote (2)),the cold designation applies to French Camp Slough. 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 Delta, and the facts described above, the Regional Board finds that the benficial uses identified in the Basin Plan for the Delta are applicable to French Camp Slough. The Regional Board also finds that based on the available information and on the Discharger's application, that the SSJID Canal, absent the discharge, is at times a seasonal and/or ephemeral waterbody. This seasonal and/or ephemeral nature of the SSJID Canal means that the 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 SSJID Canal help support the