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Water Supply Assessment Griffith Energy Storage Project the balance shows a slight surplus.Recharge from net deep percolation,subsurface inflow,and diversion made up about 85 percent of the subbasin inflows (similar to the historical water budget). The largest inflow component is deep percolation and pumping is the largest outflow component,constituting of 47 percent of the total outflow.The resulting average surplus for the projected water budget is 4,806 AFY(GEI 2021). The Project requires only 30.7 acre-feet, so there is ample water supply from the Tracy Subbasin. Table 1: Projected Tracy Subbasin Water Budget-Annual Averages (2016 to 2065) Type of Inflow Inflow(AFY) Type of Outflow Outflow Streams and Rivers 58,633 Streams and Rivers 93,446 Deep Percolation 180,334 Pumping 199,549 Small Watersheds 6,458 Subsurface 129,538 Diversion Recharge 74,015 Subsidence 608 Subsurface 107,290 Total Inflow 427,338 Total Outflow 422,532 Source:GEI 2021 2.2 CITY OF TRACY The Project site is not within the City of Tracy water service area, but as the closest public water system, the contractor can truck water from the City of Tracy to the Project site. The City of Tracy obtains water from both surface water and groundwater sources described within its Urban Water Management Plan (2020 UWMP, City of Tracy) as the following: • Purchased Central Valley Water via the Delta-Mendota Canal which is treated at the City's John Jones Water Treatment Plant. • Purchased Stanislaus River Water which is treated at the Nick C. DeGroot Water Treatment Plant, located near Woodward Reservoir in San Joaquin County. • Local groundwater via groundwater supply wells which represents 6% of the City's water supply come from the City's nine active municipal wells that overly the Tracy Subbasin. Per the City of Tracy 2020 UWMP the 2020 available water supply was estimated to be 19,527 acre-feet and is expected to increase to 40,168 acre-feet by 2045. Total demand was 19,527 acre-feet in 2020 and demand is expected to increase to 39,379 by 2045. Under normal conditions water supplies are expected to exceed demands with surplus water supply ranging from 5,374 acre-feet in year 2025 to 789 acre-feet in 2045 as shown in Table 2. With the inclusion of the Project, the surplus water would be reduced by 30.7 acre-feet resulting in a surplus of 5,343 acre-feet in 2025 and 758 acre-feet in 2045. Under normal conditions, for all years ranging from current to 2045, there is ample supply for the Project. Table 2: City of Tracy Normal Year Supply and Demand Comparison 2025 2030 2035 -0 2045 Supply Totals 26,883 28,560 31,701 34,768 40,168 Demand Totals 21,509 25,167 28,871 32,603 39,379 Difference 5,374 3,393 2,830 2,165 789 Source:City of Tracy 2020 UWMP Note: Units are in acre-feet OTETRA TECH 6 February 2023