- A proposed offstream reservoir west of Patterson could store up to 82,000 acre-feet of water.
- The project is intended to improve agricultural supply reliability, wildlife refuge deliveries, and flood protection.
- Federal, local, and regional partners are involved, with public comments accepted through January 12, 2026.
Tuesday, December 16, 2025 — The U.S. Bureau of Reclamation announced last week that it is seeking public input on a draft environmental impact statement for the proposed Del Puerto Canyon Reservoir Project in California. According to the Bureau of Reclamation
, the project would create a new offstream reservoir in Del Puerto Canyon, located in the Coast Range foothills west of Patterson and south of the Sacramento-San Joaquin Delta.
The proposed reservoir would have a storage capacity of up to 82,000 acre-feet of water. Bureau of Reclamation materials state that the project is designed to improve the reliability of water supplies for agriculture, enhance water deliveries to wildlife refuges, and provide additional flood control benefits. The reservoir would capture runoff from Del Puerto Creek and store water delivered from the Delta-Mendota Canal during wetter periods for use during drier times.
The Del Puerto Canyon Reservoir Project is being developed through a partnership between the Del Puerto Water District and the San Joaquin River Exchange Contractors Water Authority. These entities currently supply Central Valley Project water to farmland across Stanislaus, San Joaquin, Merced, Fresno, and Madera counties. Project background materials explain that water is pumped south from the Sacramento-San Joaquin Delta through the Delta-Mendota Canal, but deliveries have become increasingly variable over the past two decades due to drought conditions and pumping restrictions intended to protect fish habitat and water quality.
According to project sponsors, this variability has affected both regional economic stability and environmental conditions. The proposed reservoir would allow water to be stored during periods of higher availability and released later for irrigation, groundwater recharge, and wildlife uses. Agricultural users would pay for the stored water, while the project partners continue to pursue supplemental state and federal funding.
In 2022, the project received $15 million in federal funding through the Water Infrastructure Improvements for the Nation Act to support permitting, engineering, and design activities. Acting Regional Director Adam Nickels stated in the Bureau of Reclamation release that the project represents a significant step toward strengthening California’s water infrastructure through collaboration with local partners.
Planning documents outline a multi-year timeline. A draft environmental impact report was originally released in December 2019, followed by a public comment period. A partially recirculated draft environmental impact report was released in December 2025, with environmental review expected to be completed by mid-2026. Design work and land acquisition are planned through 2028, while construction is anticipated to begin in 2027 and take approximately six years to complete.
If built, the reservoir would cover roughly 800 acres and could support multiple functions. In addition to agricultural supply and refuge water deliveries, project materials describe potential benefits such as reduced flooding along Del Puerto Creek, groundwater recharge that could support the City of Patterson’s water supplies, and possible recreational opportunities developed in partnership with Stanislaus County and the City of Patterson.
The Bureau of Reclamation is accepting public comments on the draft environmental impact statement through January 12, 2026. Comments submitted during this period will be considered as part of the federal environmental review process before any final decisions are made.
Image from the Bureau of Reclamation’s project page.
Frequently Asked Questions
What is an offstream reservoir?
An offstream reservoir stores water diverted from a river, canal, or creek rather than blocking a main river channel with a dam. This approach can reduce some impacts to river ecosystems.
How much water would the Del Puerto Canyon Reservoir store?
Project documents state that the reservoir could store up to 82,000 acre-feet of water, with up to 60,000 acre-feet available for use in dry seasons or drought years.
Who would use the water stored in the reservoir?
The stored water would primarily support agricultural irrigation, groundwater recharge, and deliveries to wildlife refuges, according to project sponsors.
Who is funding the project?
Agricultural users would pay for the stored water. The project has also received federal funding for planning and design and is seeking additional state and federal support.
What is the next step in the approval process?
The Bureau of Reclamation will review public comments submitted by January 12, 2026, and incorporate them into the final environmental analysis before moving forward with any project decisions.
