What the Mojave Groundwater Bank Adds to California's Water Supply
The Mojave Groundwater Bank combines groundwater supply, underground storage and two pipeline routes to help California communities manage water availability across wet and dry years.
The Mojave Groundwater Bank, a water supply and groundwater storage project being developed by Cadiz, Inc. in partnership with public agencies and Native American tribes, offers California a new water source, with planned supply averaging 50,000 acre-feet annually over 50 years. Underground storage would let participating agencies bank imported water and carry over groundwater supplies for later use. Planned Northern and Southern pipeline routes would connect that supply and storage with regional water systems.
Summary
- The Mojave Groundwater Bank’s safe-yield plan provides for an average annual supply of 50,000 acre-feet over 50 years, totaling 2.5 million acre-feet.
- The Northern Pipeline is planned to carry 25,000 acre-feet annually. The Southern Pipeline would carry the other half of the Mojave Groundwater Bank’s average annual supply, with additional capacity to move water into and out of storage.
- The Mojave Groundwater Bank plans up to 1 million acre-feet of imported-water storage, alongside separate carryover storage for groundwater supplies.
- Two pipeline routes would connect Mojave Groundwater Bank supply with regional water systems, including the Colorado River Aqueduct.
A Planned Annual Supply for Roughly 400,000 People
The planned average supply of 50,000 acre-feet per year is enough to meet the annual water needs of roughly 400,000 people. The project’s figures describe separate supply and storage functions:
- Existing storage: Cadiz estimates that the aquifer system holds more than 30 million acre-feet of groundwater.
- Average annual supply: 50,000 acre-feet. The safe-yield plan provides for 2.5 million acre-feet over 50 years.
- Single-year maximum: 75,000 acre-feet. Supply may reach this level in one year, with lower volumes in other years to maintain the long-term average of 50,000 acre-feet annually.
- Imported-water storage: Up to 1 million acre-feet. This capacity would hold imported surplus water for later use, separate from the groundwater conservation supply.
The California Court of Appeal upheld the project’s reviewed state approvals in 2016, including the Final Environmental Impact Report and Groundwater Management, Monitoring and Mitigation Plan. The County groundwater management plan sets out the project’s safe-yield provisions and guides supply through continuous monitoring and adaptive management under County oversight.
Groundwater in the watershed moves toward highly saline dry lakes, where it mixes with brine and is lost to evaporation. The project is designed to conserve water while it is fresh and make it available for beneficial use. The conservation plan draws on natural recharge and recovers stored fresh groundwater already moving toward the dry lakes before it becomes saline and evaporates.
Water Agreements Connect Supply to Community Needs
Water agreements connect the Mojave Groundwater Bank’s planned supply to specific community needs. Cadiz’s August 2024 contracting announcement reported 21,275 acre-feet per year under contract, or 85% of the Northern Pipeline’s initial 25,000-acre-foot annual capacity. Five agreements signed that year provided for firm contracts over 40–50 years. By August 2026, Northern Pipeline capacity was fully committed.
According to Secure Water Alliance, 70 percent of Northern Pipeline capacity is reserved for Inland area water providers.
Local access is also built into the project’s community water commitments. The County MOU gives San Bernardino County public water systems first priority for annual supply not already bound by written agreement when the 2023 update took effect. It also provides a separate, one-time 25,000-acre-foot allocation for qualifying providers serving disadvantaged communities.
Underground Storage Saves Wet-Year Water for Later Use
The Mojave Groundwater Bank plans up to 1 million acre-feet of imported-water storage and separate carryover storage for existing contracted groundwater supplies. Participating agencies could bank surplus imported water underground or hold groundwater supply for a later year. Underground storage avoids exposing banked water directly to surface-reservoir evaporation.
Cadiz’s 2026 quarterly filing identifies an additional 150,000 acre-feet of carryover storage, separate from the imported-water capacity. Carryover storage allows participating agencies to save contracted groundwater supplies for use in a later year within the project’s 50-year safe-yield plan.
The Cadiz area has long been identified as a favorable location for groundwater storage and banking to augment the Colorado River System. The 2002 Record of Decision, covering an earlier Metropolitan Water District proposal, described groundwater banking alongside recycling and water transfers as part of a diversified dry-year supply strategy.
Two Pipeline Routes Connect Supply and Storage to Regional Systems
Cadiz’s 220-mile Northern Pipeline asset provides an existing corridor for planned water conveyance. The Bureau of Land Management approved the conversion to water conveyance across its lands in July 2026. An application for a one-mile lease for the pipeline from the State Lands Commission remains pending. As described in the August 2026 letter, the Commission staff selected a third-party contractor to review the project’s environmental record as part of that process.
The planned Southern Pipeline would extend approximately 43 miles to the Colorado River Aqueduct, making it a supply and storage option for Colorado River users. Under a May 2026 funding agreement supported by Cadiz, the Bureau of Reclamation is evaluating proposed exchanges, supply and delivery capability, and potential future federal investment in the Mojave Groundwater Bank. The evaluation examines how project water could serve the wider Colorado River system.
A proposed Arizona water supply illustrates that exchange role. Project water would enter the Colorado River Aqueduct in California, allowing an agreed amount of Colorado River water to remain available for delivery to Arizona through its existing system. Cadiz’s July 2026 MOU with CAIDD in Arizona covers up to 10,000 acre-feet annually, with the necessary exchange agreements still to be negotiated.
New Supply and Storage Expand California’s Water Options
The Mojave Groundwater Bank would combine groundwater supply averaging 50,000 acre-feet annually over 50 years with underground storage and two delivery routes. Participating agencies could use the supply to meet community needs and hold water for later years when other sources are less available.
San Bernardino County’s priority rights and one-time allocation for disadvantaged communities ensure local access is part of that plan. Together, supply, storage, and conveyance would give water providers more flexibility to serve their communities through wet and dry years.
Frequently Asked Questions
Why does Cadiz cite annual supply figures of 50,000 and 75,000 acre-feet?
The safe-yield plan provides for an average annual supply of 50,000 acre-feet over 50 years. Supply can reach 75,000 acre-feet in a single year, with lower volumes in other years to maintain that average. The 50-year total is 2.5 million acre-feet, managed under the County groundwater management plan.
What kinds of water could the Mojave Groundwater Bank store?
The project plans up to 1 million acre-feet of imported-water storage and separate carryover storage for contracted groundwater supplies. Both would let participating agencies hold water for later use below ground, away from direct surface evaporation.
How would the two pipeline routes serve water users?
The Northern Pipeline is planned to carry up to 25,000 acre-feet annually. The Southern Pipeline would carry the other half of the project’s average annual supply and provide additional capacity for water moving into and out of storage through the Colorado River Aqueduct connection.
How would San Bernardino County communities benefit?
The 2023 County MOU gives local public water systems first priority for annual supply not already under a binding written agreement when it took effect. A separate one-time allocation of 25,000 acre-feet is available through County procedures for qualifying providers serving disadvantaged communities.
What is the status of the pipeline water agreements?
Cadiz’s August 2026 shareholder letter described Northern Pipeline capacity as fully committed. For the Southern Pipeline, a July 2026 Arizona MOU covers up to 10,000 acre-feet annually. The 2026 quarterly filing also describes discussions with additional Southern California and Arizona water users.
What Communities Would Benefit From the Project?
San Bernardino County public water systems have priority access to project supply, with a separate allocation for providers serving disadvantaged communities. The project’s intended reach includes the Antelope Valley, High Desert, Inland Empire, and Coachella Valley. The Morongo Basin is included in the regional One Water planning effort involving Fenner Gap Mutual Water Company and Victor Valley Wastewater Reclamation Authority. Additional commitments include planned water for the Salton Sea Authority and Torres Martinez Desert Cahuilla Indians. The proposed Arizona exchange would supply the Central Arizona Irrigation and Drainage District.
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