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Eastern San Joaquin Groundwater Basin Groundwater Management Plan Northeastern San Joaquin County Section 2 Groundwater Banking Authority 72 Hydrogeology 2.3.8 Baseline Conditions A no-action, or baseline simulation, was conducted to predict how current groundwater and surface management practices, projected out to 2030, would impact the Basin. Groundwater modeling has shown that unless there is a change in how groundwater is used or managed, levels will continue to decline and storage will continue to be reduced. Figure 2-26 shows the corresponding simulated groundwater table for the year 2030 under baseline conditions. A large portion of the Basin is shown to have groundwater levels 60 to 80 feet below sea level. Further exacerbating the groundwater conditions, as already mentioned, is the lateral inflow of saline water from the west, which could render parts of the aquifer unusable. Figure 2-27 illustrates the approximate location of the 300 mg/l chloride concentration contour as of 1996 as well as the projected 2030 contour. Groundwater modeling has indicated that the rate of eastward movement of this line is approximately 150 to 250 feet per year. Figure 2-27 also shows the projected location of the 300 mg/L chloride concentration line by the year 2030 under baseline conditions. In other portions of California’s Central Valley, declining groundwater levels have also resulted in land subsidence. Generally, this is not a widespread problem in the Basin, but may be a localized issue in some areas. 2.4 Urban Water Demands The population of San Joaquin County is growing rapidly. The current population is expected to increase by approximately 83 percent by 2030 from nearly 600,000 to 1.1 million. While increases in urban water demands will largely be offset by the development of agricultural lands, the changes in differing water quality needs and demand patterns will further stress the ability of urban purveyors to meet the areas water needs. Because water use per acre varies by city, an analysis of each cities acreage and usage was undertaken. The area for each city was determined from 1996 DWR Land Use Surveys. In consideration of planned growth, future water demands are based on each city’s sphere of influence. Future water demands assume that by the 2030 planning horizon, each city’s sphere of influence will be fully developed and will maintain a similar water demand. Table 2-4 indicates that the total 1996 urban demand was 82,600 af annually, which is projected to increase by 146,000 af/yr to 241,100 af/yr by 2030. Unforeseeable changes such as general plans revisions, changes in population density and increased water conservation can affect the accuracy of the projected water demand. It is recommended that the projections be updated as DWR Land Use Surveys for San Joaquin County become available. 2.5 Agricultural Water Demands The agricultural water demands presented in this Plan are based on the 1996 DWR Land use survey. Based on the associated land use and crop type, applied water demands under average conditions were identified and summarized by Water District in Table 2-5. The entire applied water demand for non-urban and non-riparian vegetative areas in San Joaquin County in 1996 is approximately 1,522,000 af/yr, 954,000 af of which is needed in Eastern San Joaquin County. Table 2-5 assumes that agricultural lands outside of the urban spheres of influence will remain in production and that any agricultural lands within the urban spheres of influence will be developed by the 2030 planning horizon. The decrease in agricultural demand within city’s sphere of influence is estimated to be 132,000 af. With this decrease, the projected agricultural demand in 2030 is estimated to be 1,390,000 af per year.