SITE INFORMATION AND CORRESPONDENCE_1985-2004

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INFORMATION SHEET CITY OF MANTECA AND CITY OF LATHROP WASTEWATER CONTROL FACILITY SAN JOAQUIN COUNTY The City of Manteca and the Lathrop County Water District were governed under Order No. 91- 110, NPDES No. CA0081558, adopted 29 May 1991. This Order will be rescinded. The City of Manteca owns and operates the wastewater control facility that receives wastewater flows from the City of Manteca and some areas of the City of Lathrop. The City of Manteca is responsible for the operation and discharge from the treatment plant, while the City of Lathrop is only responsible for its portion of the wastewater collection system, and for compliance with any restrictions imposed by the City of Manteca. The City of Manteca currently discharges 5.3 mgd of treated domestic and industrial wastewater at agronomic rates to 210 acres of farm land owned by the City adjacent to the treatment plant, and-1 60 additional acres leased by the city with the excess flows discharged to the San Joaquin River. The flows to agricultural land are required to be maximized to limit the discharges to surface waters. The City has expanded the treatment plant capacity to 6.95 mgd, to treat increasing flows from population growth. This expansion included the addition of a primary and a secondary clarifier. Studies done for the City have demonstrated that the increased discharge, at the effluent limits contained in the new permit,will not have significantly impact the water quality of the San Joaquin River. Effluent and Receiving Water Limitations The"Water Quality Objectives" for.the San Joaquin Delta Basin, contained in the Basin Plan, were reviewed. Compliance with effluent limits and requirements established in this permit will meet those objectives. The effluent limits for BODS and suspended solids have been established at 20 mg/l. The limits are set to protect against the potential for adverse impact by the discharge on dissolved oxygen in the San Joaquin River during low river flows. Flows in the San Joaquin River are subject to influences from local irigation, municipal and industrial demand,water withdrawals from Clifton Court Forebay by Federal and State agencies, and tidal actions. In addition, there are proposals to modify the flow regime in the Delta to provide a more complete mix of San Joaquin and Sacramento River waters in the delta prior to transport ofthese waters south. These proposals may significantly alter the quantity and quality of water in the San Joaquin River.