A New Water Supply Option for Arizona
The Mojave Groundwater Bank offers Arizona communities a supplemental water source through a Colorado River exchange using existing regional delivery infrastructure.
Up to 10,000 acre-feet a year from the Mojave Groundwater Bank, a water supply and groundwater storage project, would supplement Arizona’s water supply under a July 2, 2026 proposal between Cadiz and the Central Arizona Irrigation and Drainage District (CAIDD). A Colorado River exchange would connect the California supply to CAIDD’s agricultural customers in Pinal County.
Summary
- CAIDD’s proposed purchase covers up to 10,000 acre-feet annually for an initial 50-year term, with renewal opportunities.
- The proposed exchange would pair Mojave groundwater delivered in California with Colorado River water delivered to CAIDD through the Central Arizona Project.
- Reclamation’s review would address the legal, technical, and accounting requirements for an interstate water exchange.
- The proposed CAIDD exchange would use the Southern Pipeline to connect Mojave groundwater to the Colorado River Aqueduct, with delivery terms set in final agreements.
CAIDD’s Agreement Plans for 50 Years of Supply
Drought and Colorado River shortages threaten water deliveries to farms, communities, businesses, and Tribes across the Lower Basin. The July 2026 memorandum of understanding would give CAIDD access to a supplemental source for Arizona. The joint supply announcement describes it as the first Mojave Groundwater Bank supply agreement with an Arizona water district.
Under the proposed terms, CAIDD would secure rights to purchase up to 10,000 acre-feet per year for an initial 50-year term, with renewal opportunities.
The proposed water price includes three components:
- A charge for the water supply.
- Operations, maintenance, and prorated power costs for conveyance to the Colorado River Aqueduct.
- A one-time prorated capital charge for dedicated pipeline capacity.
Cadiz and CAIDD also intend to pursue federal and state resources to reduce infrastructure costs.
A Water Exchange Would Supply Pinal County Farms
CAIDD serves agricultural customers in Pinal County, Arizona. The July announcement describes the irrigation and drainage district as serving approximately 87,600 irrigated acres and delivering Colorado River water through the Central Arizona Project alongside other water resources. The proposed Mojave supply is intended to supplement those resources as drought and Colorado River shortages affect agricultural deliveries.
The proposed exchange would use water supplied in California to make an equivalent quantity of Colorado River water available to CAIDD in Arizona. It would not require Mojave groundwater to travel through a dedicated pipeline all the way to Pinal County.
The delivery sequence would be:
- Produce the supplemental supply: Groundwater would be drawn from the Mojave Groundwater Bank in San Bernardino County, California.
- Convey water to the aqueduct: The Southern Pipeline would carry that supply to the Colorado River Aqueduct for a participating water agency in Southern California.
- Account for the exchange: The participating agencies would arrange and account for an equivalent Colorado River supply to be left in the Colorado River for CAIDD under the completed exchange agreements.
- Deliver through Arizona’s existing system: CAIDD would receive the exchanged Colorado River water through the Central Arizona Project to serve its agricultural customers.
Federal Review Advances Exchange Planning
Under the funding agreement announced in May 2026, Cadiz funds the U.S. Bureau of Reclamation’s technical and regulatory review of the project.
Reclamation is expected to identify the legal and operational requirements for implementing and accounting for an interstate exchange. That work would establish how the exchange fits within the Law of the River, the legal framework governing Colorado River allocation and use.
The review also covers water supply and delivery capability and technical work needed to evaluate potential future federal investment in the project.
Agreements and Construction Would Enable Deliveries
Delivering water to CAIDD requires completed water-purchase and interstate exchange agreements and construction of the Southern Pipeline facilities connecting the project to the Colorado River Aqueduct.
Cadiz, Fenner Gap Mutual Water Company, and the Fenner Valley Water Authority, in partnership with Native American Tribes, public agencies, and water districts, will construct, own, and operate the Mojave Groundwater Bank. The Lytton Rancheria partnership supports project development. The proposed Arizona supply would use this infrastructure through an interstate water exchange.
Groundwater production would remain subject to the project’s safe-yield plan and County-approved safeguards, including authority to change pumping when needed. A long-term purchase proposal does not replace those operating conditions.
Mojave Groundwater Offers Arizona a Supplemental Supply
Cadiz and CAIDD’s July 2026 proposal offers Arizona a supplemental source of up to 10,000 acre-feet annually for an initial 50 years. Mojave groundwater would enter the Colorado River Aqueduct in California, with an equivalent Colorado River supply delivered to CAIDD through an interstate exchange and the Central Arizona Project. Completed purchase and exchange agreements and Southern Pipeline construction would turn that proposed source into a long-term supply for CAIDD’s agricultural customers.
Frequently Asked Questions
How Much Water Does the CAIDD Proposal Cover?
The proposal covers up to 10,000 acre-feet annually for an initial 50-year term, with renewal opportunities. Deliveries depend on final water-purchase and exchange agreements and construction of the required pipeline facilities.
Would Mojave Groundwater Travel Directly to Arizona?
No. The proposed Southern Pipeline would carry Mojave groundwater to the Colorado River Aqueduct in California. An interstate exchange would make an equivalent Colorado River supply available to CAIDD through the Central Arizona Project.
What Would Reclamation Evaluate for the Exchange?
Reclamation is expected to evaluate the legal and operational requirements for implementing and accounting for the proposed interstate exchange. Cadiz’s funding agreement also supports review of supply and delivery capability and technical work needed to evaluate potential future federal investment in the project.
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