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City of Pleasanton 4.0 Water Agency Background Final Water Supply Assessment Stoneridge Drive Specific Plan Amendment and Staples Ranch Project Table 5-2: Zone 7 Water Supply Sources Contract Maximum Amount State Water Pro ect Sources AFA Contract Tenn/Ex iration Zone 7 SWP 1962 Contract DWR Table A 46,000 November 20, 2036 New SWP Transfers and Contract Amounts (DWR Table A Berrenda Mesa SWP Transfer 7,000 November 20, 2036 Lost Hills SWP Transfer 15,000 November 21, 2036 Kern Coun SWP Transfer 10,000 November 22, 2036 Belrid a SWP Transfer 2,219 November 23, 2036 Tulare Lake Basin Water Storage District SWP 400 November 24, 2036 Transfer Subtotal State Water Project 80,619 SWP Delive Reliabili Re ort 2002° 60,900 Other Surface Water Su I Sources Arro o Del Valle Water Ri hts Lake Del Valle 9,300 Per etual Renewal B ron-Bethan Irri ation District 2,000 December 31,2028 Reclaimed Wastewater 1,900 In Per etuit Groundwater Sources Main Basin Safe Yield 13,400 Zone 7 Sustainable Water Su I 87,500 Calculated Annuall Additional Groundwater 15,000-20,000 In Per etui Total Water Su I 100,500 - 105,500 Notes: a. Department of Water Resources -State Water Project Reliability Report 2002 using CALSIM II model data predicted that average future SWP supplies would be 75% -76% of contracted amount; Monterey Agreement DWRSIM model estimated 2020 yield at 75.57% of contract amount. Zone 7 staff agreed that 75.57% or 60,900 AFA average future yield is generally valid. b. Zone 7 Sustainable Water Supply Report, May 2007 uses 9,300 AFA for long-term water supply planning. Lake Del Valle estimated 12,000 AFA as Zone 7 reclaims local aggregate mining sites. c. Contract amount is up to 5,000 AFA, for conservative water resources planning purposes, Zone 7 uses 2,000 AFA. d 13,400 AFA is naturally recharged to the Main Basin. Zone 7 estimates Main Basin Safe Yield at 13,400 AFA and splits this among Zone 7's retail customers (7,800 AFA) and other local pumpers make up the balance. GPQ =Groundwater Pumping Quota e. Zone 7 Sustainable Water Supply Report May 2007. Zone 7 includes irrigation demands met with reGaimed wastewater from Dublin-San Ramon Water District -this WSA assumes that recycled water is always available and recycled water can be used to offset future increased irrigation demands but would not be available for potable uses. f. 15,000 -20,000 AFA Average Annual ExVaction based on historical pumping with no Net Loss to Groundwater Basin -Zone 7 pumpage equals art~cial recharge quantity from surplus surface water. g: Total of all Zone 7 Water Supply Sources Source: 2005 Zone 7 Urban Water Mana ement Plan, ada ted b PBSBJ/EIP Se tember 2007. 5.3.4.3.2. Lake Del Valle Supplies Zone 7 holds water rights in the Arroyo Valle. Within the Arroyo Valle watershed, above Del Valle Dam, winter stormwater runoff is captured and stored in the Del Valle Reservoir also known as Lake Del Valle. Lake Del Valle provides Zone 7's service area with upstream flood protection in addition to local surface water storage. The reservoir is unique in that both winter storm runoff and late winter and spring SWP supplies combine to fill it to its seasonal operational capacity. In late fall, DWR typically lowers reservoir levels in anticipation of capturing winter storm run-off and to provide additional flood capacity prior to the rainy season. Del Valle Reservoir water is available through operating agreements between Zone 7 and DWR. The average annual thirty-year historic delivery to Zone 7 from Lake Del Valle has been about 8,000 AFA.18 The future reliability and long-term yield to 2025 is calculated at 9,300 acre feet based on modeling of historic runoff data and future changes in winter season demands. It is estimated, that as growth occurs and approaches buildout winter 16 2005 Zone 7 Water Agency, Urban Water Management Plan, page 21. P:\Projec~ - WP OnIy141182.01 Staples Ranch WSA\FinahFinal WSA.doc 5-14