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WOODARD &CURRAN Table 8: Current and Projected Non-Potable Water Supply (2020-2040) Current and Projected Su I AFY Supply Type Level of 2015 2020 2025 2030 2035 2040 Pp Y yp Treatment (Existing) Recycled Water' Tertiary 429 1,159 2,103 3,061 3,775 4,479 Other Non-Potable Sources2 Chlorination 0 153 367 617 869 1,121 Source:City of Lathrop 2015 UWMP,Table 6-4(EKI,2017) Notes: 1. Recycled water supplies will be supplemented by the River Islands development if needed. 2. River Islands will have the ability to supplement City recycled water supplies with lake and river water.These supplemental sources can be used to meet up to 100%of River Islands non-potable demands if recycled water supplies are unavailable. 2.3 Water Supply Reliability Various conditions may influence the reliability of the City's water supplies in the future.The following sections evaluate the reliability of the City's supplies, including SSJID entitlements and local groundwater yield through 2040, and discusses potential constraints on these supplies. 2.3.1 SSJID Water Reliability Various conditions may influence total water supply available to SSJID.This section describes the water rights held by SSJID and the City's entitlement to the SSJID supply. As discussed in Section 2.1.1, the 1995 Water Supply Development Agreement provides the contractual relationship between SSJID and the City and includes specific rates of delivery and maximum amounts of water that SSJID is obligated to supply to the City. Due to the seniority of the water rights underlying the SCWSP, SSJID's pre-1914 appropriative rights to Stanislaus River water, the City has historically assigned a high reliability to SCWSP water. However, the recent drought has caused the City to revise its reliability projections for SCWSP water in dry years. In August 2014, due to concerns about decreasing water levels in the New Melones Reservoir, SSJID curtailed water deliveries to the SCWSP contracting cities to 80 percent of their monthly allocations. This 20 percent curtailment translated into an allocation to the City of approximately 85 percent of its annual contractual entitlement in 2014. In 2015, SSJID allocated water to each SCWSP contracting city based upon actual water use in 2013. Under this allocation scheme,the City was assigned 85 percent of its actual water use in 2013. In both 2014 and 2015, however, the City purchased less than its dry year allocation and instead relied primarily on groundwater. Given the inconsistency in SCWSP allocation in recent years and the uncertainty regarding dry year allocation in the future,the City has relied upon the dry year allocation adopted by SSJID in its 2015 UWMP(Provost&Pritchard,2016), which assumes a proportionate reduction in deliveries to urban and agricultural users. The projected urban and agricultural demands presented in SSJID's 2015 UWMP are summarized in Table 9. The urban demand is assumed to be equal to the SCWSP Phase I contract amount(31,552 AFY).Agricultural demands within the SSJID service area are projected to decrease gradually as irrigation practices become more efficient. Table 9: SCWSP Projected Water Demands Estimated Demand AFY 2020 2025 2030 2035 Contracted Urban Demand 31,552 31,552 31,552 31,552 Projected Agricultural Demand 274,100 271,800 269,500 267,200 Total 1 305,652 303,352 301,052 298,752 Source:City of Lathrop 2019 WSMP,Table 5-5(EKI,2019) Califia(0011533.00) 24 Woodard&Curran, Inc. River Islands Phase 2 Development Water Supply Assessment September 2020