RES 07163 - Laserfiche WebLink

Quota, is limited as part of our Municipal and Industrial water supply contract with each retailer. The balance of the safe yield is pumped for other municipal, agricultural and gravel mining area uses. Zone 7's pumpage for our treated water system does not use the baseline safe yield from the basin; instead we pump only water that has been recharged as a part of our artificial recharge program. Recycled water is tertiary- treated recycled water used for irrigation at the Livermore Municipal Golf Course, along Isabel Avenue, the Dublin Sports Ground and for other irrigation needs within the Valley. The City of Livermore has been using recycled water since the mid- 1960's and DSRSD started recycled water irrigation in 1999. Recycled water is a very reliable supply, however, the use of recycled water was historically discouraged due to the potential of salt buildup in our groundwater basin. The Salt Management Plan, which has been incorporated into the Groundwater Management Plan, provides tools and strategies for preventing the general salt buildup which has been slowly degrading the quality of our potable wells for decades. The current salt management strategy calls for increased groundwater recharge and use coupled with pumping of high TDS groundwater that is flowing into the Main Basin. The high TDS groundwater would be demineralized and delivered for potable water use. The concentrate from the demineralization facility would be exported via the LAVWMA pipeline that currently transports all municipal wastewater out of the watershed and directly to the San Francisco Bay. This allows for an expanded use of recycled water, the "uninterruptible" water supply. The current sustainable supply of 1,900 acre-feet is simply the current estimated amount used for irrigation. This amount is expected to increase. TOTAL SUSTAINABLE WATER SUPPLY is the sum of the previously discussed sources: The State Water Project future average delivery, 60,900 acre-feet per year; the Lake Del Valle future average yield, 9,300 acre-feet per year, the 2,000 acre-feet of BBID water per year, the safe groundwater yield, 13,400 acre-feet per year; and the recycled water use 1,900 acre-feet per year, for a total of 85,500 acre-feet per year. These sustainable water supply quantities are long -term average quantities and in dry years the supply from surface water sources will be greatly reduced. Zone 7 Water Agency stores water from our surface water sources in wet years when the SWP and LDV supplies are above average. Then in dry years, Zone 7 pumps more of the stored water out of the Main Basin or transfers water back from our Semitropic and Cawelo Water Storage District accounts. Zone 7 currently will be able to meet full deliveries even in the worst credible drought including the worst historic single -year drought and any multi -year drought of record. RECOMMENDED ACTION: Information item. 4