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REGIONAL BOARD RESPO*E(SWRCB/OCC FILE A-1483) ./ -3- STATE BOARD DRAFT WATER QUALITY ORDER PETITION FOR REVIEW OF WASTE DISCHARGE REQUIREMENTS ORDER NOS. R5-2002-0083 AND R5-2002-0084 CITY OFSTOC%TON REGIONAL WASTEWATER CONTROL FACILITY identification of toxicity in the receiving water, (3)reasonable potential based on critical conditions that are a combination of worst-case observations, and(4) an evaluation based on critical SJR flow conditions (minimum 10-year return flow). USEPA provided written and verbal comments on the NPDES permit supporting the Regional Board's ammonia reasonable potential evaluation. The Draft Order dismisses all aspects of the City's petition regarding ammonia. TERTIARY TREATMENT REQUIREMENTS The Basin Plan designates the beneficial uses of domestic supply, agricultural supply, and water contact and non-contact recreation for the SJR. The Regional Board determined that at times there is little or no dilution in the SJR in the vicinity of the discharge. Recreational uses identified in the immediate vicinity of the RWCF outfall include boating,water skiing,jet skiing, swimming, and fishing(both fish and invertebrates). A number of agricultural intakes have been identified through a search of the State Board, Water Rights Division database. Within an approximate two-mile radius of the outfall there are approximately ten diverters, including the Stockton Golf and Country Club, which draws as much as 1.15 cubic feet per second of SIR water near Smith Canal for irrigation of its golf course and landscaping. Additionally, subsistence and sports fishing/shellfish harvesting is prevalent in the immediate vicinity of the RWCF outfall. The Regional Board consulted with the California Department of Health Services (DHS) and found that, in order to protect these beneficial uses, the wastewater must be disinfected and adequately treated to prevent disease. The State Board staff agreed with these requirements and the Draft Order dismisses all aspects of the City's petition regarding the tertiary treatment requirements. The previous NPDES Permit, adopted in 1994,recognized the possibility of a health risk from pathogens in the Stockton discharge. Because the models available at the time indicated only 4:1 long-term dilution was available in the River, the Regional Board decided that Stockton should conduct a Health Risk Assessment (HRA) study to determine the pathogen impacts of the discharge prior to the Regional Board determining whether Title 22 filtration should be required. Subsequent installation of the flow monitoring station by USGS and recording of actual flows at Stockton demonstrated little or no dilution exists for days or weeks at a time. With this information it was concluded that Title 22 filtration is needed and the HRA study was not relevant. DHS recommends the wastewater be treated to tertiary standards (filtered)to protect water contact recreational uses. DHS has developed reclamation criteria, California Code of Regulations, Title 22, Division 4, Chapter 3, (Title 22) for the reuse of wastewater. Title 22 requires that for spray irrigation of food crops,parks,playgrounds, school yards and other areas of similar public access, that wastewater be adequately disinfected, oxidized, coagulated, clarified and filtered and that the effluent total coliform levels not exceed 2.2 MPN/100 ml as a 7-day median. To protect the beneficial use of domestic supply, irrigation, and water contact recreation in a receiving stream with less than 20:1 dilution, DHS recommends treatment to Title 22 standards. In addition, filtration is an effective means of reducing viruses and parasites from the waste stream.