The California Water Commission has approved nearly $219 million in additional funding to advance the Sites Reservoir project, a planned 1.5-million-acre-foot storage reservoir to protect the state against drought risks.
Announced Aug. 21 by Gov. Gavin Newsom, the funding comes as the reservoir faces rising costs but remains central to California’s water resilience strategy amid climate change.
The Sites Reservoir is located west of Maxwell in the Sacramento Valley. Its 1.5-million-acre-foot capacity will make it the state’s eighth-largest reservoir and second-largest off-stream reservoir. Off-stream reservoirs capture water during wet periods rather than blocking a river.
The 13-mile long reservoir will consist of two primary dams, seven smaller saddle dams and two saddle dikes. During wet seasons, it will pull water from two Sacramento River tributaries: Funks Creek and Stone Corral Creek.
Once operational, the reservoir will support municipal, agricultural and environmental water needs, along with flood control and renewable energy synergies, according to officials. While initial projections estimated it would serve around three million households, newer figures suggest the reservoir could benefit up to 4.5 million homes annually.
In July, the project cleared two critical permitting milestones: the U.S. Fish and Wildlife Service finalized its Biological and Conference Opinion under the Endangered Species Act for construction, and the California Department of Fish and Wildlife issued a master Lake and Streambed Alteration Agreement, authorizing modifications to local waterways and moving the project closer to construction.
Thanks to the latest funding, the project now qualifies for up to $1.094 billion in Proposition 1 funds—voter-approved in November 2014 to finance water infrastructure—adding to its $780 million in federal commitments.
This recent funding addition from the commission comes as cost estimates continue to rise for the reservoir. While original estimates put the reservoir at $4.5 billion, the cost has now increased to as high as $6.8 billion, driven by inflation, supply chain pressures and tariffs.
With the recent influx of funding, groundbreaking is expected in late 2026, and the reservoir is expected to be operational around 2032-2033. The Sites Project Authority, a joint powers entity formed in 2010 by regional water agencies and counties, will manage the construction and development of the project, and the reservoir will be operated as part of the California State Water Project (SWP).
Despite the reservoir’s off-stream design, critics argue that diverting water could still harm salmon populations, downstream habitats, and river ecosystems. A coalition led by Friends of the River points to the project’s reliance on river diversions as emblematic of outdated water-management policies, and the initiative faces continued legal and advocacy challenges over its potential ecological impacts.
The Sites project remains under scrutiny in a prolonged water rights hearing conducted by the State Water Resources Control Board, as officials assess requests to divert Sacramento River water. A status conference is scheduled for Sept. 4 via Zoom.
With major permits secured and funding largely in place, Sites could become California’s first major reservoir since 1999. However, the project still faces a final regulatory gauntlet, and the outcome will help determine whether the state can build the water infrastructure it needs to weather an increasingly unpredictable climate.
Photo by Annette Bauer from Pexels
