2025 Urban Water Management Plan

Section 6 2025 Urban Water Management Plan Water Supply Characterization City of Pleasanton Public Draft | May 2026 6-6 EKI Environment & Water, Inc. Figure 6-1 Zone 7’s Kern County Groundwater Banks: Annual Storage, Deposits, and Withdrawals 6.1.2.4.1 Semitropic Water Storage District Zone 7 initially established the water banking contract Semitropic in 1998. Water put into Semitropic is subject to a 10% leave behind. Under the current contract, Zone 7 has access to an operational storage capacity of 78,000 AF with an annual deposit limit of up to 5,883 AFY. In addition, Zone 7 can request up to 9,100 AFY of pumpback (i.e., water pumped out of Semitropic and delivered to the SWP system) and up to 8,645 AFY of SWP exchange water (i.e., water transferred between Zone 7 and Semitropic by adjusting the amounts of Table A water delivered to Zone 7 and Semitropic; the availability of this type of water depends on the SWP allocation). In certain years when SWP Table A allocation is above a certain percentage, Zone 7’s pumpback can be increased to 12,241 AFY. Between 2021 and 2025, Zone 7 stored approximately 13,500 AF (after losses) and withdrew approximately 20,100 AF from the Semitropic bank. As of January 1, 2026, Zone 7 had 79,570 AF stored in the Semitropic bank. 6.1.2.4.2 Cawelo Water District Zone 7 established the water banking contract with Cawelo in 2006. Water put into Cawelo is subject to a 50% leave behind. Under the contract, Zone 7 has access to an operational storage capacity of 120,000 AF with an annual deposit limit up to 10,000 AFY. Thus, when Zone 7 deposits 10,000 AF to Cawelo in one year, the leave behind for Cawelo is 5,000 AF, and the amount Zone 7 can later access is 5,000 AF. Zone 7 can request up to 10,000 AFY of pumpback (or SWP exchange water) from Cawelo. Between 2021 and 2025, Zone 7 stored approximately 5,000 AF after losses and withdrew approximately 8,000 AF from the Cawelo Water Bank. As of January 1, 2026, Zone 7 had 26,900 AF stored in the Cawelo bank. 6.1.2.4.3 San Luis Reservoir In addition to the non-local groundwater banking programs described above, Zone 7 can store unused Table A water in San Luis Reservoir from one year to the next (Article 56 or carryover) as long as storage