California regulators approved a key Sacramento River water-right permit for Sites Reservoir advancing a proposed 1.5 million-acre-foot storage project northwest of Sacramento. The ruling sets limits on diversions and environmental protections, while the Sites Project Authority and participating water agencies still face financing decisions and a separate hearing involving nearby creeks.
Key Takeaways
- State water regulators unanimously approved the Sacramento River diversion permit on Nov. 4, 2026
- The permit allows up to 986,000 acre-feet of annual diversions, subject to river-flow and environmental conditions
- The proposed reservoir would hold up to 1.5 million acre-feet, but that is storage capacity, not a promised annual delivery
- Financing remains unfinished, and a separate hearing on two nearby creeks is scheduled to begin in January 2027
Sites Reservoir has secured the major water-right authorization needed to begin construction, but the multibillion-dollar project is not yet under construction. The State Water Resources Control Board voted unanimously Wednesday, Nov. 4, to permit diversions from the Sacramento River into a proposed off-stream reservoir in Glenn and Colusa counties.
The ruling moves forward a project planned for decades and described by state officials as California’s largest new surface-water storage facility in more than 50 years. The approval also establishes operational restrictions that could determine how much water the system actually stores in any given year.
The reservoir’s planned capacity is 1.5 million acre-feet, a volume the state compares with the annual needs of more than 4.5 million homes. That comparison describes the size of the storage facility, not a guaranteed yearly supply to those households.
Sites Reservoir Permit Limits Sacramento River Diversions
The newly approved right allows the Sites Project Authority to divert up to 986,000 acre-feet annually from the Sacramento River. Actual collection would depend on river conditions, other water users’ rights and restrictions intended to protect fish and water quality. The authorized maximum is not a forecast of how much water would enter the reservoir each year.
Diversions are permitted from Nov. 1 through June 14, mainly when river flows are relatively high. The permit requires water to remain available for senior water-right holders and the Sacramento-San Joaquin Delta, while also setting rules for fish migration and minimum flows. Screens must be used to keep fish from being drawn into the diversion facilities.
State regulators also imposed requirements involving reservoir releases, including protections against elevated water temperatures, harmful algal blooms and mercury. The project must follow the updated Bay-Delta water-quality plan, making the permit part of a broader set of environmental restrictions.
The decision followed 32 hearing days over two years, with 41 participating parties, 60 witnesses and more than 2,100 evidentiary documents. Draft decisions circulated in March and September before the board voted. Earlier water-right permit developments had moved the proposal closer to a final decision without authorizing construction.
The approval is specific to the Sacramento River. A separate proceeding beginning in January 2027 will consider proposed collection from Funks Creek and Stone Corral Creek. That unresolved question does not erase the newly issued river permit, but it remains a distinct part of the project’s water-right process.
The 1.5 Million-Acre-Foot Reservoir Would Sit Off the River
Sites Reservoir would be built about 10 miles west of Maxwell, roughly 65 miles northwest of Sacramento. Instead of constructing a dam directly across the Sacramento River, the project would move water through existing canals and new facilities from diversion points near Red Bluff and Hamilton City to a separate storage basin.
Plans include two large dams, smaller embankments, pumping stations and pipelines. The infrastructure would allow eligible wet-season flows to be stored and later delivered through canals and river systems to participating agencies across California. The off-stream design avoids blocking the main river channel with a dam, though diversions would still affect the volume of water moving downstream.
Public irrigation districts in the Sacramento and San Joaquin valleys are among the intended participants, alongside urban suppliers serving the Bay Area and Southern California. State officials also expect water to be provided for wildlife refuges and say up to 200,000 acre-feet could be available during officially declared drought emergencies.
For farms, the project addresses seasonal differences between winter runoff and summer water demand. The broader water uncertainty facing farms remains important context, although a new reservoir would not guarantee deliveries to individual agricultural operations. The precise amount released would depend on stored supplies, contracts and operating rules. Even a reservoir capable of holding 1.5 million acre-feet would have to be filled over time using only water available under its permits.
Funding and Environmental Concerns Remain Before Construction
Project costs have been estimated at approximately $6.2 billion to $6.8 billion. California officials reported about $1.36 billion in eligible state funding in November, but the Sites Project Authority and water agencies still need to complete financial arrangements before construction begins. Approval of the water right does not settle how the remaining costs will be covered.
The Metropolitan Water District of Southern California, a potential major participant, said the ruling would help its board evaluate whether and how extensively to join the project’s financing and construction. That distinction matters because participating agencies would help pay for the infrastructure and receive access to storage under project agreements.
Project organizers have discussed beginning construction in 2027, with completion targeted around 2034. Those dates remain conditional on financing, property acquisition, contract work and other preparations. The reservoir is not an operating source of water, and completing the dams would not mean the storage basin would immediately be full.
Environmental organizations, fishing advocates and representatives of Northern California tribes have challenged aspects of the project. Critics have warned that reducing Sacramento River flows could affect salmon and other fish, while tribal representatives have raised concerns about ancestral sites and burial grounds in the proposed inundation area.
The board’s permit attempts to address some of those risks through bypass-flow thresholds, migration-related restrictions and water-quality monitoring. E. Joaquin Esquivel, the board’s chair, described the intended operating approach during the approval process: “It captures water when the river has it to spare.”
Those safeguards do not eliminate disagreements over the project’s effects. For now, the Nov. 4 decision clarifies when Sites Reservoir could draw Sacramento River water, while construction funding and the separate 2027 creek hearing remain unresolved.
Frequently Asked Questions
What permit did California approve for Sites Reservoir?
The State Water Resources Control Board approved a water-right permit on Nov. 4, 2026, allowing conditional diversions from the Sacramento River. It did not decide whether the project may also collect water from two nearby creeks.
How much water would Sites Reservoir hold?
Sites Reservoir is designed to store up to 1.5 million acre-feet of water. That is the planned capacity of the reservoir, not an amount guaranteed to be captured or delivered each year.
When could construction begin?
Project organizers have identified 2027 as a possible construction start, with work potentially continuing to 2034. The schedule remains subject to financing and other preparations.
Why are environmental groups concerned?
Opponents say diversions could harm fish and river habitats, while tribal representatives have raised concerns about cultural sites within the proposed reservoir area. The approved permit includes flow and water-quality conditions intended to reduce environmental impacts.
