What is the Eel-Russian Project Authority?

The Eel-Russian Project Authority is a joint powers authority created in 2023 by the County of Sonoma, Sonoma County Water Agency (Sonoma Water), and the Mendocino County Inland Water and Power Commission. It is governed by a five-member Board of Directors consisting of representatives from: the County of Sonoma, Sonoma Water, the Mendocino County Inland Water and Power Commission and the Round Valley Indian Tribes.

What is the purpose of the Eel-Russian Project Authority?

The Eel-Russian Project Authority’s purpose is to develop a reconfigured water diversion facility near the current location of Cape Horn Dam (part of Pacific Gas and Electric Company’s [PG&E] Potter Valley Project), to continue water diversions seasonally from the Eel River to the Russian River watershed once PG&E decommissions that project and ends its current diversion of Eel River water.

What is the Potter Valley Project?

The Potter Valley Project, located on the Eel River and the East Branch Russian River in Mendocino and Lake Counties, is owned and operated by PG&E. It includes Scott Dam, Cape Horn Dam, a trans-basin diversion tunnel, and a hydroelectric powerhouse.  Due to equipment failure, the powerhouse is no longer in operation.

As part of its original hydroelectric function, the Potter Valley Project includes facilities to divert water from the Eel River to the East Branch Russian River, and eventually to Lake Mendocino and the mainstem Russian River.

PG&E, citing financial unprofitability, intends to decommission the Potter Valley Project, which will include removing Scott and Cape Horn dams. This will end PG&E’s water diversions from the Eel River to the Russian River watershed.

What is the New Eel-Russian Facility?

The New Eel-Russian Facility is a proposed replacement of the existing water diversion infrastructure, to be undertaken by the Eel-Russian Project Authority, upon removal of Cape Horn Dam. The new facility includes new fish screens, a mechanical pump station and retaining wall, and a conduit to convey water to a reconfigured tunnel inlet. 

The New Eel-Russian Facility will continue to support water supply resiliency in the Russian River watershed by maintaining diversion of water from the Eel River during wet seasons for storage and use during the dry season. Diversions would be undertaken so as not to affect the Eel River’s ecosystem.

The New Eel-Russian Facility will be constructed, owned and operated by the Eel-Russian Project Authority.

Why is the diversion of water from the Eel River to the Russian River Watershed important?

Since 1908, the Potter Valley Project has diverted water from the Eel River to the East Fork Russian River. The diverted water flows to Lake Mendocino where it can be stored for later use, and then on to the Russian River. Until 2006, the average annual diversion was 150,000 acre-feet per year (an acre foot is 325,851 gallons of water – enough to cover one acre of land with one foot of water).

From 2007 to 2020, annual diversions decreased to approximately 60,000 acre-feet per year due to changes in PG&E’s operating license issued by the Federal Energy Regulatory Commission.

Since 2021, diversions have further declined to a range of 30,000–40,000 acre-feet per year due to failing infrastructure and seismic risks associated with Scott Dam. This water supply has become vital for hundreds of thousands of people in Mendocino, Sonoma and Marin counties, and is essential for supporting wildlife, riparian habitat and sensitive ecosystems along the Russian River.

What are the impacts of the loss of the water diversion?

If a replacement facility such as the New Eel-Russian Facility is not implemented, loss of this water diversion will pose a serious threat to businesses, cities, water suppliers, residents, tribes, farms, wildlife, riverine habitats and fisheries, all of which depend on the Russian River. The water diverted from the Eel River is part of the crucial water supply for over 600,000 people in Mendocino, Sonoma and Marin counties, and its termination would be expected to cause losses in the tens of millions of dollars per year in the affected local economies.

How much water will be diverted via the New Eel-Russian Facility?

Depending on rainfall levels and Lake Mendocino storage capacity, diversion volumes up to 30,000 acre-feet per year are anticipated (under typical wet-season conditions, the facility can reliably divert up to 50,000 acre-feet per year).

What is the status of the Eel-Russian Project Authority’s efforts?

It is anticipated that PG&E will file its Final Surrender Application with the Federal Energy Regulatory Commission on July 29, 2025. The application includes the concept of the New Eel-Russian Facility project.

While the Federal Energy Regulatory Commission considers PG&E’s surrender and decommissioning application, the Eel-Russian Project Authority will complete engineering designs for the new facility and work with other state and federal regulatory agencies to secure the permissions necessary to construct and operate the facility. 

Construction of the new facility will take place simultaneously with the removal of Cape Horn Dam, minimizing disruption to water diversions and ecological impacts to the Eel River. The design and permitting phases of the Eel-Russian Facility are expected to span several years, with concurrent regulatory and technical reviews guiding final implementation.

What is the anticipated cost of the New Eel-Russian Facility?

The total construction cost of the new diversion facility is preliminarily estimated at $50 million (as of March 2025). Russian River water users will pay for the cost of annual operations and maintenance, and support restoration efforts on the Eel River. The effort received at $2 million U.S. Bureau of Reclamation grant for engineering design. Additional federal and state funds are being pursued to help fund design, permitting and construction costs.

What are the milestones leading to this project?

1908 – Construction of Potter Valley powerhouse; start of water diversions to generate power

1930 – PG&E acquires and operates the Potter Valley Project

2019 – PG&E announces intent to decommission the Potter Valley Project, including water diversion

2022 – PG&E submits initial plan and schedule for “surrendering” Potter Valley Project

2023 – Eel-Russian Project Authority is formed to develop the New Eel-Russian Facility

2025 – PG&E releases Draft Final Surrender Application; submittal of Final Application anticipated for  July 29, 2025

What is the Federal Energy Regulatory Commission?

The Federal Energy Regulatory Commission (sometimes referred to as FERC) is an independent agency regulating natural gas and hydropower projects, as well as the interstate transmission of natural gas, oil and electricity. The commission’s authorization is required for PG&E to surrender its license and decommission the Potter Valley Project, remove the dams and provide the opportunity for the New Eel-Russian Facility project to be implemented.