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San Joaquin County Community Environmental Setting,Impacts,and Mitigation Measures Development Department Groundwater and Groundwater Quality used is described in detail and compared against historical water use in the project area. Premining Period. Under premining or current conditions,the project area consists of approximately 217.5 acres of irrigated almond orchards. _ Evapotranspiration of applied water(ETAW)rates were obtained from DWR Bulletin 113-3 (April 1975), Table 25. Using values for a 10-to 12-inch rainfall zone, ETAW for almonds is 1.7 ac-ft/acre. Based on these data, the total use of water over the project area is approximately 370 ac-ft/year. This estimate may be ' higher than the actual consumptive use from the agricultural operations because it does not consider the quantity of irrigation water that may seep into the ground and recharge the aquifer. As mentioned in section 3.G, "Surface Water, Stormwater, and Water Quality,"the primary water supply for this irrigation is surface water from the Delta-Mendota Canal via the Del Puerto Water District. Therefore, it is assumed that no groundwater is used during the premining period .. for agricultural uses. Stages I-A through III-B. For mining Stages I-A through III-B,consumptive use of water for the aggregate processing,dust control,concrete production,and truck washing would be approximately 425 of/year(380,000 gallons/day). This freshwater consumptive use does not include moisture retained in the product y (gravel). As mining displaces irrigation-related consumptive use,the overall water budget would reflect a net increase in water use from a low of approximately 370 ac-ft/yr under current conditions to a peak of approximately 889 ac-ft/yr during Stage III-B (Table 3.H-1). Consumptive use during many of these stages is generally similar because of evaporation from the settling pond and evapotranspiration from crops grown over the reclaimed pits. For all of these stages, estimated water consumption would range from approximately 636 to 889 ac-ft/yr(Table 3.H-1). On-site wells and pumps would supply groundwater for the mining and reclamation operations. Stages IV-A and IV-B. In both Stages IV-A and IV-B,the South Pit would be reclaimed. During Stage IV-A,North Pit 3 would be backfilled to the groundwater level, and a portion of it(24.8 acres)would be used as an agricultural pond. The remaining acreage of North Pit 3 (10.2 acres)would be reclaimed with agricultural crops. The net consumption of water in the project area during Stage IV-A would decrease from the peak during Stage III-B including evaporative losses from the agricultural pond and irrigation of 183 acres of undisturbed and reclaimed land used for agricultural purposes. Estimated consumptive use for Stage IV-A would be approximately 454 ac-ftlyr, _ which is approximately half of the peak mining period use. Implementation of Stage IV-B instead of Stage IV-A would involve the reclamation of the entire North Pit 3 acreage (35 acres)and would not include an agricultural pond. Therefore, the consumptive use for this stage would represent only evapotranspiration from agricultural crops grown on the undisturbed and reclaimed lands(208 acres). Estimated consumptive use for Stage IV-B would be approximately 353 ac-ft/yr,which is less than the premining consumptive use w DeSilva Gates Quarry Project Draft Environmental Impact Report 3,H-11 ' AS 05705.05