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5.4.6 Springs <br /> During the 1987 geologic/hydrogeologic site investigation, springs were not identified on the site <br /> or within 1 mile of the proposed landfill site <br /> 5.4.7 Groundwater Quality <br /> 5.4.7.1 Regional Groundwater Quality <br /> The landfill site is located within the San Joaquin Hydrologic Region, Eastern San Joaquin <br /> Subbasin. The subbasin encompasses 707,000 acres (DWR, 2003). According to California's <br /> Bulletin 118 for the San Joaquin River Hydrologic Region, 2003, groundwater measurements <br /> over the past 40 years have shown a continuous decline in groundwater levels in the Eastern San <br /> Joaquin County. As a result of declining water levels, poor quality water has been moving <br /> eastward along a 16-mile front on the east side of the Delta. The degradation was particularly <br /> evident in Stockton where a saline front was moving eastward. Large areas of elevated nitrate in <br /> groundwater exist within the subbasin located southeast of Lodi and south of Stockton. For the <br /> entire basin, 689 public supply water wells were sampled from 1994 through 2000. Samples <br /> analyzed indicated that 523 wells (76%) met the state primary MCLS for drinking water. The <br /> others (24%) had constituents that exceeded one or more MCLS. These included: inorganics <br /> (aluminum, arsenic, manganese, iron, and total dissolved solids), radiological, nitrates, <br /> pesticides, and VOCs. <br /> Calcium-magnesium bicarbonate or calcium-sodium bicarbonate types characterize the majority <br /> of the basin. Bicarbonate is the predominant anion in the eastern part of the basin. <br /> According to the Bulletin, groundwater quality throughout the region is suitable for most urban <br /> and agricultural uses with only local impairments. <br /> 5.4.7.2 Site Groundwater Quality <br /> The groundwater beneath the NCRC&SL site is sampled quarterly. The groundwater wells at <br /> the landfill did not indicate impact until three VOCs were found at well G-4 in July 2002. <br /> Historical results and the most recent groundwater sampling results are attached in Appendix B. <br /> North County RC&SL Page 23 of 48 Public Works/Solid Waste <br /> JTD County of San Joaquin—November 30,2004 <br />