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Eel River Project Authority chooses pump station as preferred diversion facility

A dam, with water pouring into a river.
Cape Horn Dam, where proponents hope to build a pump station that will divert water from the Eel to the Russian River after Cape Horn and Scott Dam are decommissioned.

Proponents of a post-dam diversion have decided what kind of structure they’ll ask for when PG&E submits its license surrender application for the Potter Valley Project. A number of questions have yet to be answered, especially about sediment management and how much water will continue to flow from the Eel into the Russian River. But after months of committee meetings and analyses across a wide spectrum of interest groups, a new joint powers authority decided unanimously on March 19 to pursue a pump station that would divert water from the Eel River into the Russian River during high flows.

The Eel Russian Project Authority consists of representatives from Sonoma Water, the county of Sonoma, Mendocino County Inland Water & Power Commission (or IWPC, which is itself a consortium of local governments and water agencies), and the Round Valley Indian Tribes. It is negotiating with PG&E during the process of decommissioning Scott Dam, which impounds Lake Pillsbury, and Cape Horn Dam, near the tunnel that diverts water from the Eel into the Russian River. It will also have the legal authority to own, build and operate the new diversion facility where Cape Horn Dam is now.

In August, Russian River water users and the Round Valley Indian Tribes asked PG&E, which owns and operates the Potter Valley Project, to include one of two possible alternatives in its license surrender application to the Federal Energy Regulatory Commission, or FERC. PG&E said it wanted to negotiate with a governmental body, so the new Authority was formed. PG&E is not bound to accept the Authority’s request to include its preference in its submission to FERC, and FERC can accept it, reject it, or ask for modifications. As James Russ, representing the Round Valley Indian Tribes, noted, “PG&E seems to change their mind quite often, and sometimes it can be very quickly. They can do a 180 degree turn. So I just wanted to make sure we’re on the same page at this point in time.”

In a March 13 letter to the editor in the Press Democrat, Dave Canny, PG&E Vice President for the North Coast Region, wrote that the company “still supports the concept of a diversion with fish passage;” but that it was not interested in seeking a nonpower license from FERC on behalf of the proponents, “which would cause delays and expenses for our customers.”

Though PG&E is often referred to as “a black box,” the IWPC hired engineering consultant Tom Johnson to design two possible diversion facilities up to 30%, to get enough information about each to decide which one was worth pursuing.

The two alternatives are a pump station, a series of seven pumps that would divert the water during the wet season, and a roughened channel, or an 800-foot-long section of the river that would be engineered with a 3% slope and filled with carefully placed boulders to simulate a somewhat natural flow and transfer the water using gravity.

Though the roughened channel would not use electricity, environmental groups opposed it from the outset because they feared that if anything went wrong, it would be more likely to harm fish passage than a pump malfunction, which would have a more direct effect on water users in the Russian River watershed. Johnson extolled the benefits of the pump station in his report to the Eel Russian Project Authority directors at their March 19 meeting. “It was just superior because of the lower gradient, less energy that needed to be dissipated by the channel itself, (and it) didn’t necessarily have big twelve and fourteen foot boulders with water crashing about,” he reflected. “All in, the pump station was always going to be a better fish passage alternative.”

Johnson said the channel also had the potential to cause more sediment buildup than the pump station. At the 30% design level, the two options looked like they would cost about the same to build, though the margin of error was too high to be sure. Running the pump station will cost water users an estimated $5 to $10 an acre foot, but the lower cost of water using the roughened channel scenario was the only criteria where the channel won out over the pumps, in the opinion of the members of the technical advisory group that studied the matter.

And, while there are examples of roughened channels being used in waterways, they are rarely used in the mainstem of a river as powerful as the Eel in winter. Johnson noted that pumps are a little more tried and true. “The pump station, while it is a complicated object,” he acknowledged; “It’s a pump station. Y’all are water agencies. Y’all know how pump stations work.”

The station would use about one megawatt of power per year to operate, and it would be equipped with a backup generator in case it fails during a winter storm, which is likely in rural Potter Valley.

James Russ, representing the Round Valley Indian Tribes, noted that the Potter Valley Project dams aren’t the only ones coming down in the larger region. “Probably everybody in this room knows that the dams up on the Klamath are being removed,” he said. “Are there lessons to be learned from what’s going on up there?”

David Manning, Environmental Resources Manager for Sonoma Water, replied that there will be lessons to be learned about restoration from the Klamath, including, “how fish will deal with the ongoing impacts post dam removal, and how quickly they recover from the restoration of the lakebed. Those are all great examples that can be taken from the Klamath dam removals and brought to the Eel for this project.”

Sonoma Water has received a $2 million Aquatic Ecosystem Restoration grant from the U.S. Bureau of Reclamation for planning to bring the design of the pump station up to 60%. Manning expects to hire an expert this year, and for the work to take another two and a half years. The cost share is 65% federal and 35% local.

The actual dam removal could take place over the course of one year, which would release a huge amount of sediment all at once, or over the course of a few years, which would spread out the impact. Johnson said a lot of modeling needs to be done to plan for various scenarios, but, “Whether that is something PG&E is going to do at some point in time is unclear. It needs to be done, and I’m certain it will be done before the final designs for a new diversion facility are in place. It’s just unclear who and when, and who’s going to take the lead on making that happen.

And a team of attorneys is working on the water supply agreements, “Because that is a burning question,” Johnson noted. “Everyone needs to know, how much water?”

Local News
Sarah Reith came to Mendocino County in 2008 and worked as a reporter and freelancer, joining KZYX as a community news reporter in 2017. She became the KZYX News Director in March, 2023.