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Eastern San Joaquin Groundwater Basin Groundwater Management Plan Northeastern San Joaquin County Section 8 Groundwater Banking Authority 141 Integrated Conjunctive Use Program Operations and Maintenance costs are expected to steadily increase to $5.75 million by 2015. The cost of the groundwater injection and extraction facilities is unknown at this time. The estimated cost of raw water delivery is approximately $200 per af, and the cost of delivery of fully treated water is expected to be about $350 per af. Past groundwater studies in the region show that the maximum, sustainable, long-term yield from the aquifer is 0.75 to 1 acre-foot per acre per year. The City of Stockton selected 0.6 af per acre per year as the target groundwater extraction rate which corresponds to an extraction amount of 40,000 af per year to combat historic overdraft conditions and the intrusion of saline groundwater into the underlying Basin. The DWSP will also include an aquifer storage and recovery (ASR) program to better meet long-term needs of the City of Stockton. The City of Stockton is currently preparing a project level EIR/EIS with an anticipated groundbreaking date of 2008 and water delivery scheduled for 2010. The aggressive schedule is indicative of the uncertainty in final revised State Maximum Contaminant Level (MCL) for arsenic. At present the City of Stockton meets or exceeds the Federal MCL for arsenic; however, more conservative State regulations may force numerous well closures forcing the City of Stockton to rely more heavily on the DWSP and alternative sources. Subsequent phases include a 10 MGD pilot ASR program to bank treated surface water in the underlying aquifer. The pilot ASR program involves retrofitting up to 10 existing wells for injection and extraction at an estimated cost of $200,000. After the completion of the pilot program, costs will be determined for an expanded program to serve as a groundwater bank. In the Feasibility Study, three potential banking sites were identified: Site A, north of Alpine Road and west of Highway 99, site B, south of Alpine Road and west of Highway 99, and site C, located along the Southern Pacific Railroad - Figure 8-25 (City of Stockton, 2003). 8.3.3 SEWD Water Treatment Plant Expansion The current capacity of the Dr. Joe Waidhofer Water Treatment Plant (SEWD Treatment Plant) is 45 MGD, and the capacity of the planned expanded facility is 60 to 65 MGD. Currently turbidity occasionally limits production to 30 MGD resulting in an average yearly production of approximately 41,000 af. An expanded SEWD Treatment Plant is expected to supply up to 62,000 af per year. Currently, raw water sent to the SEWD Treatment Plant originates from either New Hogan Reservoir on the Calaveras River or New Melones Reservoir on the Stanislaus River. The combination of available water from these sources totals 90,099 af per year. The additional 28,000 af could be used for groundwater recharge and extracted during dry years. The estimated cost for the expansion is $26.9 to $33.4 million (SEWD, 2003). 8.3.4 CSJWCD Surface Water Delivery Program CSJWCD holds CVP contract entitlements for water from New Melones Reservoir with the USBR. The total amount available to CSJWCD under the contract is 80,000 af/yr, 49,000 of which is said to be a firm supply. Because of current USBR operations of the New Melones Reservoir, in water year 2003, an above normal year for precipitation in the Stanislaus River watershed, the contract amount received was 10,000 af. CSJWCD delivered this amount in its irrigation system while SEWD did not receive any allocation in water year 2003. The CSJWCD irrigation system currently has the infrastructure capabilities to deliver approximately 35,000 af/yr for direct irrigation through a series of ditches and natural creeks, including Littlejohns, Temple, Lone Tree and Duck Creeks. The current system can be expanded to deliver up to 50,000 af/yr should water become available. Figure 8-26 depicts the CSJWCD irrigation system.