A New Reservoir for a New Climate

By Sarah June 23, 2022

Author: Jerry Brown, Sites Project Authority Executive Director

In a year of unprecedented drought, a policy brief recently released by the independent Public Policy Institute of California (PPIC) affirmed the need to modernize our state’s aging water infrastructure and highlighted the opportunities to better manage our water supplies by capturing excess storm and flood outflow from the Sacramento River.

Today there is no existing infrastructure in place to capture and store truly excess water flows from the Sacramento River when they happen for use in subsequent dry years. Even in dry California, there are times when flows in the Sacramento River are huge, presenting an unrealized opportunity to capture and store significant amounts of water generated by stormwater and flood flows. This can be done safely for fish and is where Sites Reservoir would play a major role in adapting California’s water management for the changing climate.

In recent years and under future climate change scenarios, the West Coast of the United States will experience atmospheric river events. These storms can produce powerful runoff in the Sacramento River, at times overtopping the flood control system, causing tremendous flooding and damage throughout Northern California. It is these periods of large rain fall where the PPIC’s brief Tracking Where Water Goes in a Changing Sacramento–San Joaquin Delta demonstrates significant amounts of uncaptured water are and will continue to be available to augment water supplies for flexibility in managing the state’s water.

The May 2022 analysis states, upstream and in-Delta uses consume less than 20 percent of runoff from the Sacramento River, with water exports accounting for 10 percent during wet years. The remaining 70 percent of water results in outflow, which travels through the Sacramento–San Joaquin Delta and to the ocean.

We must maintain sufficient flow through the Delta to support a healthy ecosystem. But when the excess storm and flood water comes in wet times, we need to be prepared with infrastructure to capture the excess water.

To put this in perspective, if Sites had been in place during storm events since 2017, many flood impacts could have been avoided and the reservoir would have stored nearly one million acre-feet of water to help mitigate the impacts of the current difficult drought situation.

What is the Sites Reservoir?

Sites will be a multi-benefit, off-stream water storage facility, located north of Sacramento in rural Colusa and Glenn counties. Sites will serve to capture and store stormwater and flood flows in the Sacramento River after all other water rights and regulatory requirements are met.

The Sites Reservoir Water Availability Analysis submitted to the California State Water Resources Control Board (SWRCB) in May 2022, conservatively demonstrates there is anywhere between an annual average of 871,000 acre-feet and 1,174,000 acre-feet of uncaptured outflow from the Sacramento River. With an estimated average annual withdrawal of approximately 300,000 acre-feet and a total storage capacity of approximately 1.5 million acre-feet, Sites can store the excess outflow and leave sufficient flows for other projects and future ecosystem needs. Sites would only withdraw water from the river when safe for fish and after all other demands are met.  

The PPIC’s report emphasized the need to the modernize the state’s water infrastructure. California’s current water infrastructure was not designed with future climate conditions in mind. But extensive modeling has indicated Sites performs best and provides even greater water supply benefits to farms, people, and the environment of California, under even the most challenging climate change scenarios.

Sites is Critical for the environment

The drought protections for fish and fowl provided by Sites will be the first of its kind. The environment’s water and storage space will be managed by the state through its Proposition 1 investment, to be used when and how needed. The design of Sites releases most of the stored water back to the river during the dry periods when fish, fowl, farms and families need it most. The water set aside in Sites for the environment will help aquatic species and habitats withstand dry year conditions. The storage flexibility from Sites, working in concert with our existing water management systems, could help us respond more rapidly and in an adaptive fashion to the changing hydrologic conditions and the changing needs of the environment. As long as there is a California, there will be a dedicated portion of Sites for the environment.

What’s next for the Site Reservoir Project

Sites has made significant progress over the past several years. We achieved critical funding objectives, including an invitation to apply for a $2.2 billion WIFIA loan. The California Water Commission issued a Feasibility Determination in late 2021, an important regulatory deadline that was achieved without exception. And the Sites Project Authority and our federal partners are undergoing a revised Draft Environmental Impact Report/Statement process and expect to finalize that process early 2023. There are additional regulatory and permitting processes underway now.  Our goal is to begin construction in 2024 and be in operation by 2030.  We have no time to waste.

With crushing drought conditions upon us, it is all the more evident that we need Sites Reservoir to create a more resilient water supply for California. Sites is the modern, smart, 21st century storage future generations need to get through the next century.