Potter Valley Project

Federal regulations require that PG&E submit a final license surrender application by 2025, which would enable it to begin decommissioning the project.

In 1920, Snow Mountain Water and Power began construction on a larger dam on the Eel River, 12 miles (19 km) upstream from Cape Horn.

This reservoir serves a critical function during dry years as it is drawn down to compensate for reduced diversions from the Eel River system.

Since then, late summer water has been released from Cape Horn Dam at rates roughly mimicking or exceeding natural flows in an attempt to mitigate the impacts to fisheries.

The vast majority of the water arrives as winter rain between December and April, with a smaller, less reliable amount furnished by snowmelt and groundwater through June.

Project regulations require that the gates at Scott Dam be opened between October 16 and April 1, for safety reasons during the winter months.

Winter storms fill the reservoir, which provides only very limited flood control, because the average annual runoff of 400,000 acre-feet (490,000,000 m3) is over five times the project storage capacity.

[10] Because there is very little natural runoff in Potter Valley and the local geology is non-conducive to groundwater storage, the PVID is the only constituent that depends solely on Eel River water.

In addition to agricultural, domestic and industrial uses, project water helps to maintain a minimum dry season flow of 150 cubic feet per second (4.2 m3/s) in the Russian River, serving for recreational, aesthetic and fishery enhancement purposes.