SITE INFORMATION AND CORRESPONDENCE

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INFORMATION SHEET -4- STOCKTON COGENERATION COMPANY SAN JOAQUIN COUNTY waste sump and from the RO concentrate. The limits have been set to comply with federal regulations for steam electric power generating point sources listed under 40 CFR Part 423.15. Oil and Grease—A daily maximum limit of 20 mg/l and a monthly average limit of 15 mg/l has been set for the discharge from the internal low volume waste sump and the RO concentrate discharge. The limits have been set to comply with federal regulations for steam electric power generating point sources listed under 40 CFR Part 423.15. Monitoring The following is a discussion of significant changes from the previous permit: Receiving Water-Monitoring stations R-1 and R-2 were modified from the previous permit and stations R-3 and R-4 have been eliminated. R-1 is now located in North Littlejohns Creek 50 ft upstream from the point of discharge and R-2 is now located in North Littlejohns Creek 50 ft downstream from the point of discharge. Receiving Water Monitoring is no longer required in French Camp Slough. The compliance point for the ambient receiving water temperature limit has been moved in an effort to better protect the beneficial uses of North Littlejohns Creek and to comply with Basin Plan requirements. The determination of the impact due to temperature from the facility on North Littlejohns Creek will be evaluated at the point of discharge into North Littlejohns Creek. Due to the fact that North Littlejohns Creek is intermittent, there are times of the year when the receiving water is dominated by SCC effluent. Of 24 bi-monthly samples in 1999, temperatures 75% of the year were below 70°F, with the remaining 25% ranging between 70°and 74°F. This Order provides for a time schedule for meeting the receiving water limitation. The Board considers the application of a water quality objective that has never been applied to North Littlejohns Creek as a new interpretation of the Basin Plan. Three Species Chronic Toxicity Monitoring—Chronic toxicity monitoring shall be conducted to determine whether the effluent is contributing toxicity to North Littlejohns Creek. The facility will be required to conduct chronic toxicity monitoring on a quarterly basis. If the facility proposes to modify chemical usage, the Discharger must notify the Regional Board prior to the modification. Priority Pollutant Analyses—There is inadequate information available to determine if the discharge causes, has the reasonable potential to cause, or contribute to an exceedance of water quality objectives for priority pollutants, including CTR and NTR constituents, constituents for which drinking water maximum contaminant levels (MCLS) prescribed in the California Code of Regulation, and temperature. The data collected will be used to determine if there is a reasonable potential for the effluent to cause or contribute to violations of any narrative or numeric receiving water objectives for these constituents. The permit can be reopened and the Board may include effluent limitations for constituents of concern.