Feds OK plan to keep more water in Lake Pillsbury reservoir

The east fork of the Russian River flows from the Potter Valley hydroelectric generation plant in Potter Valley. (KENT PORTER/ PD FILE, 2014)
The east fork of the Russian River flows from the Potter Valley hydroelectric generation plant in Potter Valley. (KENT PORTER/ PD FILE, 2014)

Federal authorities have granted temporary flow reductions aimed at keeping more water in Lake Pillsbury, a small but crucial reservoir high in the Mendocino National Forest that supplies water to the Eel River, Lake Mendocino, the Russian River and the people, farmers and fish dependent on them. The move is aimed at ensuring healthier river flows into the fall.

The changes, implemented Monday by PG&E, which owns the reservoir, will remain in effect until June 18, providing sufficient time for the Federal Energy Regulatory Commission to collect and review public comments on the changes and make a final determination. A 15-day comment period began Monday. The amount of the flows will vary depending on factors that include how much water is in the lake.

Potter Valley Irrigation District board member Janet Pauli is happy with the decision and optimistic it will remain in place until Dec. 1, as requested. The district is dependent on a water diversion from the Eel River.

“It’s important,” she said of the effort to conserve the water until the next rainy season.

PG&E sought the change largely to maintain at least 10,000 acre feet of water in the reservoir through the fall in order to prevent its banks from sloughing, downstream turbidity and potential blocking of its outlet. There currently is about 38,500 acre-feet of water in the reservoir. An acre-foot is about enough water to fill a football field a foot deep, or supply one household with 893 gallons of water a day for a year.

Environmentalists, water agencies, fisheries officials and farmers hope that holding back water in the reservoir now will mean there will still be water flowing in the fall.

The reduction in flows down the Eel and Russian rivers is expected to harm fish in the short term, but it could save them from perishing later, federal regulators noted in their decision.

To allow more water to remain in the lake, regulators had to approve lowering the minimum river flows at two locations on the Eel River and one at the east fork of the Russian River, which is fed by a diversion from the Eel River.

The diversion shunts water from the Eel River through a milelong mountain tunnel and into a PG&E power plant, where it turns giant electricity-generating turbines before flowing into Potter Valley irrigation ditches, the east fork of the Russian River and then into Lake Mendocino.

The district is the first to be hit by reductions in the diversion’s flows, but those flows also affect farmers, residents and wildlife throughout the entire Russian River system.

David Keller of Friends of the Eel River called the plan, which has wide-spread support, a good short-term, emergency solution for conserving water during the drought.

But he said long-term changes need to be made to how the dam is managed to stave off future problems. That would include better monitoring of winter storms rather than assuming they will come and letting water out of the dam unnecessarily, an issue that’s been raised by legislators regarding Lake Mendocino, Keller said.

“It should be operated more effectively,” he said.

Published by: The Press Democrat

Author: Glenda Anderson

Published: May 21, 2015

Read article on Press Democrat’s website.