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Administrative Draft Environmental Impact Report Gill Medical Center Project decrease in groundwater storage of 113,000 acre-feet per year, 164,000 acre-feet per year, and 223,000 acre-feet per year, respectively. Over the last 50 years, the amount of groundwater in storage has decreased by an average of 34,000 acre-feet per year, or a total of 1,700,000 acre-feet. The largest annual change in groundwater storage of 223,000 acre-feet per year shown in Table 4.12-1 represents 0.4 percent of the total groundwater in storage in the Subbasin. The cumulative reduction of groundwater in storage over the last 50 years is 3.2 percent of the total groundwater in storage in the Subbasin. Vineyard water demand in the Central Valley is approximately 2.5 acre-feet per acre so the current water demand for the 32 acres of vineyard area on the Project site is about 80 acre-feet per year.Table 4.12-4 shows the available groundwater supply (i.e., the amount of water currently used to irrigate the 32 acres vineyard) compared with the projected water demands for the Project at full build out. Potable water demand and irrigation water demand are anticipated to be 42 acre-feet per year and 30 acre-feet per year, respectively. However, the irrigation demand is anticipated to be fully offset with recycled water from the onsite wastewater treatment plant. In addition, approximately 12 acre-feet of the applied irrigation water is expected to infiltrate into the subsurface below the root zone and percolate back to the water table.Thus, the net Project demand for groundwater from the aquifer is projected to be 30 acre-feet per year, which is substantially less than the 80 acre-feet per year that are currently used to irrigate the vineyard area on the Project site.The Project water demand is diminished compared to the overall water demands and changes in groundwater storage presented in Table 4.12-1 and, as such, would have a miniscule and imperceptible effect on the groundwater basin. Table 4.12-4.Available Water Supply Compared with Demand for Various Hydrologic Conditions(acre-feet per year) Normal Year Dry Year Multiple Dry Year Available Groundwater Supply 80 80 80 Potable Demand 42 42 42 Irrigation Demand 30 30 30 Recycled Water 30 30 30 Return to Aquifer 12 12 12 Net Demand 30 30 30 The WSA determined that the water demand and available supply do not change during normal years, dry years, or multiple dry-year periods.The WSA concludes that there will be sufficient water available for the Project during single dry year and multiple dry year periods over at least the next 20 years, in accordance with requirements of the Water Code, and that water levels in the groundwater basin will not drop to depths that would affect beneficial uses of the aquifer. The net Project groundwater use of 30 acre-feet per year is less than the existing baseline groundwater volume of 80 acre-feet per year used for irrigation of the vineyard. Thus, the Project would not decrease groundwater supplies, would not impede sustainable management of the groundwater basin, and would Hydrology and Water Quality 4.12-26 October 2021