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in the SSJID drainage system flows west through laterals into the French Camp Canal located at the western <br /> boundary of the city which eventually flows north into the French Camp Slough and ultimately drains into the San <br /> Joaquin Delta,which is located northwest of the city. Existing road and railroad crossings of the French Camp <br /> Canal are undersized(i.e.,they constrain the flow and can cause the back up of water)and require modification <br /> (e.g., expansion)to accommodate future peak buildout flows from the City of Manteca(City of Manteca 2003a). <br /> The City is planning to implement these new facilities through its Storm Drain Master Plan(2006). <br /> The WQCF site and portions of the wastewater collection system, effluent outfall, and recycled water distribution <br /> system pipelines in the southwest portion of the project area are located in the French Camp Outlet Canal(FCOC) <br /> and Drain 7 subsheds. The FCOC flows from south to north along the Union Pacific Railroad(UPRR)tracks from <br /> north of State Route 120(SR 120)to the French Camp Slough. The FCOC collects water from all city drains and <br /> laterals and is the backbone of the city's stormwater drainage system. The Drain 7 serves approximately 1,600 <br /> acres from the Spreckles complex north of SR 120 to the southernmost portion of the FCOC. <br /> Groundwater Hydrology in the Project Area <br /> The City is located in the Eastern San Joaquin County Groundwater Basin(ESJCGB), a sub-basin of the San <br /> Joaquin Valley Groundwater Basin. DWR classified the ESJCGB as a basin in a critical condition of overdraft in <br /> DWR Bulletin 118-80(City of Manteca 2005). <br /> Groundwater levels historically drop during severe drought periods and recover in subsequent wet periods; <br /> however,the Manteca area has experienced a long-term drop in groundwater levels resulting from local <br /> groundwater pumping and severe overdraft in the central and eastern portions of the groundwater basin. The City <br /> of Manteca continues to reduce overdraft of groundwater supplies and maintain historical reliability of <br /> groundwater resources by limiting groundwater usage to meet the safe aquifer yield for the area identified as 1.0 <br /> acre-foot per acre per year by the City's Public Works Department Engineering Division(City of Manteca 2006). <br /> The City of Manteca historically extracted groundwater at a rate of approximately 2.4 acre-feet per acre per year. <br /> Recent groundwater extraction rates for the City are shown in Table 4.9-2. As shown in Table 4.9-2,the City of <br /> Manteca relied exclusively on groundwater resources for domestic water supplies from the years 2000 through <br /> 2004. <br /> Table 4.9-2 <br /> City of Manteca Groundwater Extraction Rates <br /> Year <br /> 2000 2001 2002 2003 2004 <br /> Acre-Feet per Year 12,609 12,974 13,516 14,451 14,933 <br /> Percent of Total Water Supply 100 100 100 100 100 <br /> Source:City of Manteca 2005 <br /> Within the Manteca area,groundwater levels are relatively high as a result of the low topographic elevation and <br /> proximity to the San Joaquin River and Delta channels to the west. High groundwater can be influenced by water <br /> levels in the San Joaquin River, subsurface groundwater flow from areas of higher elevation to the east, and local <br /> irrigation practices. Groundwater recharge also may occur as a result of irrigation of agricultural lands and <br /> infiltration from streams flowing west out of the Sierra Nevada. The recharge occurs in areas with permeable <br /> materials that allow infiltration of water along streams, alluvial fans, and foothill areas (City of Manteca 2003b). <br /> DEIR EDAW <br /> City of Manteca 4.9-5 Hydrology and Water Quality <br />