COMMITTEE AGENDA MEMORANDUM
Water Supply and Demand Management Committee
Government Code § 84308 Applies: Yes ☐ No ☒
(If “YES” Complete Attachment A - Gov. Code § 84308)
SUBJECT: title
Receive and Discuss Information regarding the Status and Potential of Various Groundwater Banking Projects.
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RECOMMENDATION: Recommendation
Receive and discuss information regarding the status and potential of various groundwater banking projects.
Body
SUMMARY:
Valley Water’s groundwater banking program has played a vital role in managing the County’s excess imported supplies in wet years and in meeting drought demands. Semitropic Water Bank is currently Valley Water’s only out-of-county groundwater banking program. The recently adopted Water Supply Master Plan 2050 reflects the need to maintain banking storage capacities, and the diversification of groundwater banking program will reduce risks inherent to any singular program. Additionally, diversification may provide additional put and take capacities to optimize Valley Water’s existing imported water supplies. Since the April 2025 update to the Water Supply and Demand Management Committee, staff continued to coordinate with various entities across California that are managing existing or developing new banking programs. This update highlights the latest on Semitropic Water Bank, Willow Springs Water Bank, and Irvine Ranch Water Bank.
Semitropic Water Bank
Valley Water entered into a groundwater banking agreement with Semitropic Water Storage District (Semitropic) in 1997. The agreement provides Valley Water with 350,000 AF of total storage capacity, a minimum of 31,675 acre-feet (AF) of annual recharge capacity, and a minimum of 31,500 AF of annual recovery capacity. The current agreement with Semitropic expires in 2035.
1,2,3-Trichloropropane (TCP) was detected in certain recovery wells in Semitropic, which can impact Semitropic’s ability to recover stored water to the California Aqueduct in a future prolonged drought. Semitropic began the design of a consolidated treatment facility for one of its distribution systems to treat recovered water for 1,2,3-TCP, and it is currently conducting a pilot to test the treatment technology. Banking partners, including Valley Water, expect updated information on the design and construction of the treatment system and its impact on long term operations later this year.
Willow Springs Water Bank
Willow Springs Water Bank (WSWB) is a proposed groundwater banking and conjunctive use project located in the Antelope Valley near Rosamond, CA, within Antelope Valley-East Kern Water Agency’s (AVEK’s) service area. The project is managed by CIM group, a private real estate and infrastructure owner and operator. WSWB has a permitted total storage capacity of up to 1 million AF, recharge capacity of 250,000 AF per year, and recovery capacity of 225,000 AF per year. The total project cost is estimated at $581M for the full buildout. WSWB is intended to include public-benefit functions of ecosystem support and emergency storage capacity. Producing these public benefits conditionally provides WSWB with $128M of grant funding through the California Water Storage and Investment Program. Valley Water had previously expressed interest in the project.
Valley Water staff is working with the WSWB project team to develop a non-binding Memorandum of Interest to memorialize Valley Water’s interest in participating. Staff is also seeking additional information necessary to evaluate the feasibility of the project for Valley Water, including conveyance capacity to and from the project, water quality, participants’ contribution to ecosystem public-benefits, and operating costs. The project is undergoing CEQA review for a new pipeline alignment to the California Aqueduct, pursuing a turnout connection to the California Aqueduct, and conducting groundwater modeling. The results of these efforts will inform Valley Water’s assessment of project feasibility.
Irvine Ranch Water Bank
In 2024, Valley Water executed a water exchange program agreement with Irvine Ranch Water District (IRWD). Under the agreement terms, Valley Water will deliver its supplies for recharge into IRWD’s water bank located in Kern County, of which half the supply will be transferred to IRWD and the other half made available for return to Valley Water. The program provides 10,000 AF of storage capacity for water to be returned to Valley Water and a second priority return capacity of 3,333 AF per year. The program term goes through 2035, and Valley Water pays no upfront costs.
IRWD receives State Water Project supplies from a member agency of Metropolitan Water District of Southern California (Metropolitan), and Metropolitan’s approval is required for the implementation of the program. To gain Metropolitan’s approval, Valley Water staff engaged with IRWD and Metropolitan staff to adjust the agreement, and finalized terms for an amended agreement were agreed to earlier this year. The parties will need the Department of Water Resources’ approval to implement the water exchange program.
Other Projects
Imported Water staff continues to engage with other potential partners on banking opportunities, including Sacramento Regional Water Authority and AVEK, which will diversify banking operations and improve imported supply reliability during droughts. Staff will keep the committee apprised of future program development and agreement renegotiation as they materialize.
ENVIRONMENTAL JUSTICE IMPACT:
There are no environmental justice impacts associated with this item.
ATTACHMENTS:
Attachment 1: PowerPoint
UNCLASSIFIED MANAGER:
Manager
Vincent Gin, 408-630-2633