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4. Summary - <br /> Quarterly groundwater level and quality monitoring of two identified aquifer zones(a shallow and a deep <br /> zone)commenced in 1994 and mining of the Lone Tree II phase area commenced in 1998. Water level <br /> data,collected semi-annually from 1960 through 2011 by the California Department of Water Resources, <br /> are also available for one shallow zone well. <br /> The extensive available shallow groundwater level record shows that water levels observed since 1994 are <br /> within the range of historically observed levels, although recently have declined to the lowest levels since <br /> the early 1990's. Groundwater level elevations in the area of Teichert's Vernalis plant suggest _ <br /> predominantly southeasterly groundwater flow direction also severely depressed water levels due to the <br /> recent drought(2012-present)appear to have caused reversed groundwater flow in fall 2014. <br /> Groundwater levels observed in the deep wells are typically lower than in the shallow zone,and exhibit <br /> greater seasonal and annual fluctuation than groundwater levels in the shallow wells. In the early 2000's, — <br /> groundwater levels in the deep zone noticeably declined, likely in response to reported increased pumping <br /> of local deep irrigation and industrial production wells. In the mid 2000's, substantial recovery of <br /> groundwater levels occurred,however,seasonally high water levels remained below those observed in the - <br /> mid to late 1990s. Since 2013,groundwater levels have approximately declined another 15 feet. <br /> The groundwater quality record documents stable conditions in both the shallow and deep aquifer zones. _ <br /> Shallow groundwater is generally of Ca-Na/HCO3-Cl type and deep groundwater is of Ca-Na/HCO3-SO, <br /> type. The overall content of soluble minerals is slightly higher in shallow zone groundwater than in deep <br /> zone groundwater. Elevated nitrate concentrations in groundwater,documented since pre-mining times to <br /> the present,are most likely attributable to historical and ongoing agricultural land use in the area. In — <br /> summary,the existing data record shows no indication that mining operations have changed groundwater <br /> quality to date. <br /> © WHOORi 6 SCALMANINI <br /> 8 CON SJLTNG ENGINEERS <br />