SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

REGIONAL BOARD RESPONSE (SW2CB/OCCFILE.4-1483) PETITION FOR REVIEW OF WASTE DISCHARGE REQUIREMENTS 16- ORDER NOS. R5-2002-0083 AND R5-2002-0084 CITY OF STOCKTON REGIONAL WASTEWATER CONTROL FACILITY Board used primarily options (A) and (B), either using USEPA water quality criteria or the explicit policy of the Regional Board. "72. The diazinon effluent limitation is derived from Department of Fish Game recommendations. In relying on DFG recommendations, the RWQCB failed to explain the rationale for accepting these DFG recommendations in the record and there is no evidence to support that the DFG recommendations are applicable or appropriate for the RWCF, or for the receiving waters." The Regional Board adopted the effluent limitations for diazinon in the manner expressly authorized by the Clean Water Act regulations and the Basin Plan. See Response to Petition Paragraph 67 above. It was reasonable for the Regional Board to use the CDFG criteria because the science and evaluation that went into development of the diazinon criteria represents the most recent, peer-reviewed recommendation for criteria protective of aquatic toxicity. In addition, CDFG implemented USEPA study protocols in the development of the criteria. "73. The effluent limitation for chloroform is derived from the EPA National Recommended Ambient Water Quality Criteria for Human Health, which is 5.7 ugA (63 Fed Reg. 68354, 68357.) The 5.7 ug/7 is not an adopted criterion for chloroform, and was rejected in the final CTR. The RWQCB Is use of an unadopted and superseded criterion is arbitrary and unreasonable and results in adoption of new water quality objectives without compliance with Porter-Cologne, CEQA, and the APA." The Regional Board adopted the effluent limitations for chloroform in the manner expressly authorized by the Clean Water Act regulations and the Basin Plan. See Response to Petition Paragraph 67 above. The Basin Plan contains a narrative toxicity water quality objective, which states: "All waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human,plant, animal, or aquatic life." (Basin Plan,page III-8.00.] The narrative toxicity objective and the Basin Plan Policy for Application of Water Quality Objectives provide that the objective may be translated using numerical limits published by other agencies and organizations. In addition, in implementing a narrative objective the Regional Board must comply with 40 CFR 122.44(d)(1) and frequently applies option (B), i.e.,using USEPA's ambient water quality criteria in deriving numeric limitations to protect receiving waters from toxicity. If the City and/or the State Board believes the use of USEPA's ambient water quality criteria for chloroform at this time is inappropriate because it is being reassessed, then the Regional Board could use other criteria developed by other agencies and organizations. For example, the Cal/EPA Office of Environmental Health Hazard Assessment has published the Toxicity Criteria Database, which contains cancer potency values for chemicals, including chloroform. The OEHHA cancer potency value for oral exposure to chloroform is 0.031 milligrams per kilogram body weight per day(mg/kg-day). Using standard toxicological factors used by OEHHA and EPA of 70 kg body weight and 2 liters per day water consumption, this cancer potency value is equivalent to a concentration in water of 1.1 µg/L(ppb) at the 1-in-a-million cancer risk level. This risk level is consistent with that used by DHS to set de minimis risks from involuntary