Court strikes down challenge to proposed major California reservoir

June 7, 2024

The largest proposed California reservoir in nearly half a century is set to continue moving forward after a county court ruled that the proposal complies with environmental regulations and procedures, denying a December petition from six environmental groups.

In July, Gov. Gavin Newsom signed a law streamlining challenges to infrastructure that required courts to make decisions within 270 days instead of the typical years such cases usually take. Newsom used that authority to fast-track consideration of the Sites Reservoir project in November.

None of the groups has announced plans to appeal the ruling, which would need to be filed by June 7. If the ruling stands, the next step for the project will be securing permits and water rights, a process planned for 2025 ahead of a construction start date in 2026. Operations are slated to start in 2032.

The off-stream Sites Reservoir plans call for a capacity of 1.5 million acre-feet to provide more flexibility in California’s water supply and add resilience in the face of changing climate conditions.

State projections show future precipitation increasingly coming as rain rather than snow, and current water management systems are not designed to capture large amounts of rainfall and runoff. As a rain-fed storage solution, Sites Reservoir will be capable of collecting water from extreme storm events, keeping it in storage for communities, farms and environmental uses during dry periods.

The reservoir will be near Maxwell, a rural farming town in Colusa County, about 65 miles northwest of Sacramento, with the area’s grasslands and rolling foothills providing good characteristics for off-stream water storage. It will capture and store stormwater flows from the Sacramento River after fulfilling all other water rights and regulatory requirements.

Sites Reservoir complements major reservoirs such as Shasta, Oroville and Folsom, which are integral to both the Central Valley Project and the State Water Project. By connecting with and optimizing water releases from this existing network, the new reservoir will work in concert with the existing statewide water supply.

Unlike traditional reservoirs, it will not dam or obstruct any major river system, nor will it threaten fish migration or spawning. Sites Reservoir will also be the first in California to allocate some of its water specifically for environmental purposes, aiding wildlife and habitats during droughts. These features include:

  • Providing up to 372,020 acre-feet of storage for environmental uses.
  • Increasing freshwater flow into the Sacramento River Delta during dry periods, helping to manage salinity in the estuary.
  • Helping maintain cold water for salmon and improve conditions for fish in the upper Sacramento River.
  • Enabling federal and state natural resource agencies to support environmental needs and priorities when other water sources are scarce or unreliable.

The U.S. Department of the Interior announced an additional $67.5 million in funding for the project a day before the court ruling allowing it to move forward.

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