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Limbo for Mendocino County water transfer clouds outlook for key Russian River source

The Russian River’s sprawling, manmade delivery system for drinking and irrigation water has for decades relied on a share of the flow in the Eel River, miles to the north in Lake County.

In years past, up to 22 million gallons have been siphoned from the Eel through a system of pumps, pipes and reservoirs and sent south into the East Fork of the Russian River through a mile-and-a-half tunnel blasted into a mountain more than a century ago.

But the future of that cog in the Russian River machine, long seen as critical for farmers, ranchers and rural residents reliant on the river in Mendocino County and northern Sonoma County, is now in limbo.

The water transfer also has generated hydroelectricity as it passed through a small powerhouse in rural Potter Valley and on into Lake Mendocino near Ukiah.

Efforts by federal fisheries regulators to bolster declining salmon and steelhead runs in the Eel River have slashed those diversions in half since 2007. And the drought cut those diversions by another fifth this year, as water regulators seek to maintain supplies in Lake Pillsbury, formed by a dam across the Eel River.

Potter Valley Powerhouse, map
Potter Valley Powerhouse, map

They may be eliminated permanently in the future as a result of PG&E’s decision not to renew its license for the 113-year-old Potter Valley powerhouse when it expires next year, leaving the state of all water transfers from the Eel River uncertain.

A coalition including government officials from Sonoma Water, the environmental group Cal Trout, agencies in Mendocino and Humboldt counties and the Round Valley Indian Tribe, have agreed to work on a “two-basin solution” that would allow for some continued water diversions while shoring up habitat for imperiled migratory fish.

The spillway gates at Scott Dam are running full blast thanks to heavy rain and snow in the Lake Pillsbury watershed, Thursday, March 14, 2019. (Kent Porter / The Press Democrat) 2019
The spillway gates at Scott Dam are running full blast thanks to heavy rain and snow in the Lake Pillsbury watershed, Thursday, March 14, 2019. (Kent Porter / The Press Democrat) 2019

Part of their plan, to remove 99-year-old Scott Dam in Lake County and drain Lake Pillsbury, would result in the largest dam removal project ever in the region to restore access to salmon and steelhead spawning grounds in the upper Eel.

It would take a host of state and federal approvals, extensive technical studies, new diversion infrastructure and costs estimated in the hundreds of millions of dollars, with no clear guarantee on outcome.

“It’s extremely unpredictable,” said David Keller, Bay Area Director of Friends of the Eel River, and a longtime proponent of dismantling the river’s dams. “Somebody’s going to have to figure out who pays for it and what that looks like.”

Even then, diversions would only be made in the winter months, forcing Russian River consumers to change how they store and use water, he said.

Grant Davis, general manager of Sonoma Water, the wholesale supplier for more than 600,000 people in Sonoma and northern Marin counties, called on the state to recognize the historic connection between the two watersheds.

He also wants support for some $3 million in studies needed to determine if a new project can be developed to divert water in an environmentally safe and smart manner.

“Whole communities have become dependent and come up on that system,” so losing the Eel River transfers would be “a dramatic change in events” for those who get their water from the Russian River, he said.

You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com.

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