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Draft Supplemental Environmental Impact Report Page IV.G-7 Forward Inc. Landfill 2018 Expansion Project to coarse sand and gravel. Sedimentary formations underlying the Victor Formation include additional, productive aquifers. Groundwater within 1 mile of the site is tapped by irrigation and domestic wells, and most such wells in the vicinity are generally drilled to a depth of several hundred feet. Many of the sedimentary formations underlying the Victor formation have productive confined aquifers.In order to develop adequate flow,most of the agricultural irrigation wells in the area are at least 500 feet deep. Groundwater recharge to the unconfined aquifer,both regionally and locally,is from local rainfall and stream infiltration,while the deeper, confined aquifers are recharged by rivers, reservoirs, and surface runoff along the western base of the Sierra Nevada. The project area is not in a General Plan-designated substantial groundwater recharge area, although some infiltration and percolation to the groundwater system is expected along Littlejohns Creek.' Since before the early 1960s,the San Joaquin hydrologic basin has experienced overdraft as a result of heavy pumping. In the Central San Joaquin Irrigation District, which encompasses Forward Landfill, water levels have dropped approximately 70 feet in the past 40 years. Beyond the trend of historical over-drafting (removing more groundwater than is naturally recharged) from the aquifer,the San Joaquin Valley's groundwater basins have the tendency for water levels to show seasonally variations. Seasonal fluctuations reflect the rainy and dry seasons. Rainy season infiltration raises the water table, and dry season pumping lowers the water table. Seasonal fluctuations in the project area are on the order of 5 to 10 feet due to a distinct rainy season and dry season. During the rainy season infiltration raises the water table and during the dry season drawdown by water well users lowers the water table. The declining water levels throughout the Stockton area have induced the eastward movement of poor-quality water from the delta sediments. Migration of these saline waters had already impacted the utility of groundwater as far east as Stockton at the time of a 1981 study by the U.S. Geological Survey (USGS) (SJCFCWCD, 1990). The San Joaquin County Flood Control and Water Conservation District has documented a decline in water quality for the Stockton area due to a general increase in chlorides. The regional water quality in the area around Forward Landfill meets the State's Drinking Water Standard. The water is a calcium-magnesium/bicarbonate water type, with TDS concentrations under 500 mg/1. Groundwater Uses and SuIply The designated beneficial use of the groundwater in the landfill area, as specified in the Basin Plan, are domestic and municipal supply, agricultural supply,industrial service supply, and industrial process supply. Groundwater wells in the area are used primarily to supply water for agricultural and domestic purposes. 'Hydrogeological investigations at the Forward Landfill show that recharge along the course of the south fork of LittleJohns Creek,which crosses that property,has a significant influence on water table depth,gradient, and flow direction in the localized creek area.