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California Regional Water Quality Control Board - <br /> Central Valley Region <br /> Robert Schneider,Chair Gray Davis <br /> Winston H.Hickox Governor <br /> Scemran'for Sacramento Main Office <br /> Environrnenial [ s swrcb.ca.govl-awgc65 <br /> Protection Iyn n IRe t S ramento.California 95827-3003 <br /> Rt ,mp l •FAx(916)255-3015 <br /> SEP 0 3 2002 <br /> TO: MICHAEL LEVSNVIRONMENT HEALTH FROM: THOMAS R. PINKOS <br /> Staff Counsel PERMIT/SERVICES Acting Executive Officer <br /> DATE: 30 August 2002 SIGNATURE: �'`161N!✓a P1.Jty <br /> SUBJECT: PETITION FOR REVIEW OF WASTE DISCHARGE REQUIREMENTS, ORDER NO. <br /> R5-2002-0083 (NPDES NO. CA 0079138)AND CEASE AND DESIST ORDER NO. <br /> R5-2002-0084, CITY OF STOCKTON, REGIONAL WASTEWATER CONTROL <br /> FACILITY, SAN JOA QUIN COUNTY <br /> (SWRCB/OCC FILE A-1483): REGIONAL WATER BOARD RESPONSE <br /> INTRODUCTION <br /> The State Water Resources Control Board (State Board) has determined that the petition, dated <br /> 28 May 2002, filed by the City of Stockton(hereafter Discharger, City, or Petitioner), to review Waste <br /> Discharge Requirements (WDR) Order No. R5-2002-0083 (NPDES No. CA 0079138) and Cease and <br /> Desist Order R5-2002-0084, for the Regional Wastewater Control Facility(RWCF) is complete. The <br /> State Board has requested that the Regional Water Quality Control Board, Central Valley Region <br /> (Regional Board)provide the record for decision, as well as respond to the petition. The administrative <br /> record was submitted to the State Board on 1 August 2002. This memorandum constitutes the Regional <br /> Board's response to the petition. <br /> The over riding technical issue in the Stockton NPDES permit is determining whether dilution should be <br /> granted. Despite over a decade of study,there is still no agreement on how to determine the dilution <br /> available for the City's discharge. The City developed seriously flawed water quality models that <br /> concluded there is assimilative capacity available for all pollutants. In contrast, the Regional Board <br /> found; that by analyzing net river flows, there was likely very little dilution during above average wet <br /> years. The Regional Board found it was reasonable to assume that the San Joaquin River(SJR) flows <br /> would be less during critically dry years,resulting in little or no dilution. Notwithstanding, for <br /> individual pollutants,there may be minimal assimilative capacity in the SJR, but background conditions <br /> and the City's discharge contain many pollutants, and the combined impact of those pollutants cannot be <br /> assessed. Therefore, the Regional Board concluded that dilution should not be granted for most <br /> constituents. Given the severely impaired condition of the SJR and the presence of threatened and <br /> endangered species in the vicinity of the discharge, the Regional Board found this conclusion to be <br /> reasonable and necessary to protect the beneficial uses of the receiving waters. <br /> California Environmental Protection Agency <br /> ri: Recvc7ed Paper <br />