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Eastern San Joaquin Groundwater Basin Groundwater Management Plan Northeastern San Joaquin County Executive Summary Groundwater Banking Authority 6 4. Groundwater levels in the early 1990s had declined to the point where a number of wells throughout the Basin could not be operated. The severity of the situation forced many pumpers to construct new deeper wells. Table ES-4 Components of a Groundwater Management Plan Plan Component Recommended by AB 3030 Required by SB 1938 Plan Sections Control of saline water intrusion X 2, 3, 4, 5, 8 Management of wellhead protection and recharge areas X 4 Regulation of contaminated groundwater X 4 The administration of a well abandonment X 4 Elimination of groundwater overdraft X 2, 3, 4, 5, 8 Replenishment of groundwater X 2, 3, 4, 8 Groundwater monitoring X X 5 Operation of a conjunctive water management system X 3, 8 Well construction standards X 4 Financing groundwater management projects X 6, 7 The development of groundwater management partnerships X 1, 4, 7, 8 Coordination of land use planning and groundwater management X 4 Description of participation by interested parties X 1, 7 Plan to involve agencies overlying the basin X 1, 7 Basin Management Objectives X 3 Basin management entity and area map X 1 Sources: California Department of Water Resources Division of Planning and Local Assistance http://wwwdpla.water.ca.gov/cgi-bin/supply/gw/management/hq/ab3030/main.pl California Department of Water Resources Draft 2003 Update Bulletin 118 Figures ES-2 and Figure ES-3 depict the Fall 1993 and Spring 1998 groundwater level contours respectively. The Fall 1993 contour represents the lowest groundwater level contours recorded in the Basin historic record. The Spring 1998 contour represents the recovery of the Basin following years of above average and severe precipitation. The result of long-term groundwater overdraft is two fold: significant decline in groundwater levels and increased accretions from area waterways. Although increased accretions to the groundwater basin from high quality surface water sources are desirable, accretions in the western fringes of the Basin from the Lower San Joaquin River and older marine geologic formations are generally undesirable primarily due to elevated salt levels. Based on a simplified groundwater balance, as shown in Table ES-5, the net groundwater overdraft is estimated to be approximately 160,000 af/yr.