The Potter Valley Project (PVP) is a 9.4-megawatt hydropower project located on the Eel River and the East Branch Russian River in Mendocino and Lake Counties, about 15 miles northeast of the city of Ukiah. The Project is currently licensed to Pacific Gas and Electric Company (PG&E) and the license expires on April 14, 2022. Project features include Lake Pillsbury, a 76,876 acre foot storage reservoir impounded by Scott Dam; Van Arsdale Reservoir, a 700-acre foot storage reservoir impounded by the Cape Horn Diversion Dam; and a tunnel and penstocks that divert Eel River water to the project’s powerhouse located in Potter Valley. Water released from the project is regulated by Endangered Species Act requirements in the project’s license to mimic the natural water flows of the Upper Mainstem Eel River.
From the powerhouse, the diverted water flows into the East Branch of the Russian River, where it continues into Lake Mendocino, just outside Ukiah. Releases from Lake Mendocino go into the East Fork of the Russian River. The project currently diverts an average of approximately 62,500 acre-feet of Eel River water into the Russian River a year.
Cape Horn Dam, which forms Van Arsdale Reservoir, has a fish ladder. Van Arsdale is impacted by high-flow events, which require gravel removal; Cape Horn Dam will require some type of modification or re-engineering as part of the relicensing process for the facility. Scott Dam, which forms Lake Pillsbury, has no fish ladder and completely blocks native fish from accessing key habitat in the Eel River’s headwaters.