Sites Reservoir is a potential new offstream reservoir that would be located about 78 miles northwest of Sacramento in the eastern foothills of the California Coast Range. It would harness winter flood flows from the Sacramento River, divert the water west and pump it into a deep, 14,000-acre reservoir formed in the Antelope Valley. The valley now is used for cattle grazing.
The concept is for Sites to be operated in coordination with other Northern California reservoirs such as Shasta, Oroville and Folsom to increase the flexibility, reliability and resiliency of the State Water Project (SWP) and federal Central Valley Project.
Water would arrive to Sites Reservoir via the existing Tehama-Colusa and Glenn-Colusa canals, as well as a new pumping station on the Sacramento River. The water would then be released into the Sacramento River to augment natural flows and releases from other reservoirs.
Proponents say they favor the Sites location because it is not on a major river so it wouldn’t directly affect fish migration and it is north of the Sacramento-San Joaquin Delta, meaning it could provide flexibility for water quality and environmental flows. Critics say diversions for the reservoir could take more than 60 percent of the Sacramento River flows at times, with potentially significant impacts to the river’s riparian and aquatic ecosystems and the many fish and wildlife species that depend on those ecosystems.
In 2020, the Sites proposal was modified, with its estimated costs reduced from $5.1 billion to $3 billion. The new plan calls for a reservoir with a capacity of 1.5 million acre-feet (down from the original 1.8 million acre-feet plan), which would drop the average annual amount of water the reservoir could deliver from 505,000 acre-feet to 243,000 acre-feet. Other changes included elimination of an 18-mile pipeline east to the Sacramento River to fill the reservoir and a hydropower pumping station.
In dry and critical years, Sites Reservoir would provide help to preserve the cold water pools in Lake Shasta to help critically endangered salmon and improve water quality conditions in the Sacramento River, according to the Sites Project Authority, the group of regional entities, water agencies and counties formed in 2010 to pursue the development and construction of the project.
The Sites Reservoir proposal first emerged as part of the second stage of the State Water Project in the 1980s. The first stage was comprised of Oroville Dam, the California Aqueduct and the associated hydroelectric plants and pumping stations. All this infrastructure was built during the 1960s to mid-1980s to provide an annual water yield of 2.23 million acre-feet.
State Water Project Stage II included Sites Reservoir along with a peripheral canal to divert water around the Delta and southward, and various other projects that would feature Northern California river diversions.
Renewed interest in the Sites Reservoir project has been linked to diminished water supply and delivery shortfalls due to drought, Delta pumping restrictions, population growth and climate change in California.
Sites Reservoir – officially referred to in studies by DWR and Bureau of Reclamation as the North-of-Delta Offstream Storage Project (NODOS) – is planned to improve water supply reliability during drought periods when operated in conjunction with existing reservoirs. In all, the primary objectives are:
- Improve water supply reliability for agricultural, urban, and environmental uses
- Increase survival of anadromous and endemic fish populations
- Improve environmental and drinking water quality in the Delta
Where is Sites?
Sites, a small community in Colusa County in Northern California, is surrounded by rolling hills and set in a basin of grasslands used primarily for grazing cattle. The town was named for John Sites, a pioneer rancher in the late 19th century. Although no township exists today, the community of a handful of families and ranchers still maintain a proud heritage.
And, even though a reservoir would inundate the basin, most of the residents support the water storage proposal.
If the reservoir were to be built, the surrounding foothills would provide a natural barrier to the basin and facilitate the flooding of the long and narrow Antelope Valley. The reservoir would be fortified by several dams. The main dams, Sites and Golden Gate, would be built across Stone Corral and Funks creeks. Sites Dam, the larger of the two would stand about 310 feet high. Six smaller saddle dikes would hold in the north end of the lake, according to Reclamation.
Sites Project Authority Board
The Sites Project Authority Board consists of members representing water districts, irrigation districts and municipalities in the Sacramento Valley working to advance the project. These include: Colusa County Water District, Glenn County, Reclamation District 108, Colusa County, Glenn-Colusa Irrigation District, Tehama-Colusa Canal Authority, Westside Water District, city of Roseville, Placer County Water Agency, city of Sacramento and Sacramento County Water Agency.
In addition to the Sites Project Authority Board, the project includes a reservoir committee made up of water agencies and irrigation districts across the state that are investing in a share of the water.
Since 2017, the Metropolitan Water District of Southern California’s board of directors has authorized $5.7 million in investments to access as much as 50,000 acre-feet of annual water yield from the Sites project. In 2018, the project received $816 million from the Proposition 1 water bond and secured a $449 million loan from the U.S. Department of Agriculture. In 2019 the federal Water Infrastructure Improvements for the Nation Act appropriated $6 million to Reclamation for the Sites project.
In late 2020, Sites Reservoir was awarded $13.7 million through the Water Infrastructure Improvements for the Nation Act. The action coincided with Reclamation’s release of the final feasibility report for the North-of-the-Delta Off-stream Storage Investigation.