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INFORMATION SHEET 2 CITY OF STOCKTON REGIONAL WATER QUALITY CONTROL PLANT SAN JOAQUIN COUNTY in non-point source controls being implemented in agricultural and urban areas; (2) Hearir,;s on Delta Salinity Standards, which may lead to increased water flow in the river; and (3) Additional requirements placed on water projects to provide increased water flows. With these additional actions to inprove water quality, the Board believes the water quality objective will be met. The Discharger is unable to meet the limitation for ammonia without proceeding with plant improvements. Due to the time requirements to plan and construct the treatment facilities, a companion Cease and Desist Order provides a time schedule to meet the limitation. Effluent and Receiving Water Limitations BOD/Ammonia/TSS/Dissolved Oxygen- The water quality objective for dissolved oxygen in the San Joaquin River in the vicinity of Stockton is now 6 mg/I from I September to 30 November, as outlined in the Water Quality Control Plan for Salinity, San Francisco Bay/Sacramento-San Joaquin Delta Estuary, dated May 1991, and 5 mg/I during the rest of the year. The river model found that existing treatment processes caused violations of the water quality objective in the fall and spring, due to high mass loading of BOD and ammonia, and that addition of activated sludge/nitrification units to provide effluent concentrations meeting a 30-day average for CBOD of 5 mg/I and ammonia of 0.5 mg/I will significantly improve water quality. The Discharger is unable to meet the limitation for ammonia without proceeding with plant improvements. Due to the time requirements to plan and construct the treatment facilities, a companion Cease and Desist Order provides a time schedule to meet the limitation. With additional actions to decrease contributions to the oxygen deficit (e.g. improvements to non-point source controls being implemented in agricultural and urban areas, and increased water flows), which are discussed above, the Board believes the water quality objective will be met. The daily maximum limitation for ammonia was set at 5 mg/l. The limit will allow for some excursions from the 0.5 mg/I average, but be protective against acute and chronic toxicity. The 30-day average TSS limitation remains at 10 mg/l, whenever the water quality objective for dissolved oxygen in the San Joaquin River is not being met. Total Residual Chlorine (TRC)- The existing permit required effluent not exceed a monthly average TRC concentration of 0.02 mg/I, or a daily maximum concentration of 0.05 mg/l. The proposed permit requires that the discharged effluent not exceed a daily TRC average concentration of 0.018 mg/I and a monthly TRC average concentration of 0.011 mg/l. The time averaged limitations are proposed rather