Saturday, September 23, 2023

The Nuts and Bolts of Removing the Dams Along the Eel River

This shows the angled face of Scott Dam. The angle was added because of a landslide during construction. Photo credit: Kyle Schwartz/CalTrout. Permission to use from CalTrout.

On August 22, 2023, CalTrout’s Charlie Schneider and Dam Safety Expert David Keller presented the purpose and plans behind current proposals to remove the dams currently standing along the Eel River.

PG&E wants to begin removal of Scott Dam on the Eel River in 2028. Aging infrastructure led to the decision to abandon the Potter Valley Project, and Scott and Cape Horn Dams. PG&E has determined that it will be less expensive to remove the dams than it would be to repair the power generation facility. CalTrout’s Charlie Schneider said, “FERC licensed dams are complicated beasts. Transbasin diversion increases the complexity.”

PG&E stopped generating electricity from the Potter Valley Project in 2001. It had been losing $5 to $10 million per year. Three members of the Russian River Water Forum Planning Group, the Mendocino Inland Power and Water Commission, Sonoma Water, and the Round Valley Indian Tribes, have submitted a proposal to PG&E to purchase the diversion facility. PG&E is expected to pay for the cost of decommissioning the dams, and the company says it has set aside funds for this.

CalTrout is firmly on the side of removing Scott and Cape Horn Dams on the Eel River as soon as possible. The RRWF Planning Group (CalTrout is a member) has a two-fold mission: 1) to restore the health of the Eel River, and 2) to ensure that some form of diversion of Eel River water into the Russian River continues. Many on the Eel River side of the RRWF advocate for ceasing the diversion altogether. CalTrout hopes that someday the Eel will be restored to its former life as one of California’s great salmon rivers.

Biologists say that decommissioning the dams and opening the headwaters habitat is necessary to increase the number of fish in the Eel River. Currently only about 3,000 to 5,000 salmon return annually, as opposed to approximately 800,000 salmon per year in the old days.

Restoration of the ecosystem at Lake Pillsbury is initially estimated to cost $20 million. Dam removal advocates say there should still be opportunities for recreation along the river after the dams are removed. The Pike Minnow, a non-native fish that preys on juvenile salmon, is established in Lake Pillsbury and in the river between Lake Pillsbury and Van Arsdale reservoir, and will need to be removed.

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David Keller, dam removal and infrastructure specialist retired from Friends of the Eel River, spoke about the shifting ground beneath Scott Dam and Lake Pillsbury. Scott Dam was built in 1922. There were problems with landslides during construction. A large boulder that was to be the anchor of one side of the dam tumbled out of place before the concrete was poured. The dam face had to be redesigned with an angle, because the anchor they were planning to use was lost in a landslide and the engineers had to come up with an alternative. Scott Dam was constructed on an unstable foundation. Bartlett Springs earthquake fault runs under Lake Pillsbury. The only safe remedy is to lower the level of water.

This past Spring, PG&E decided not to close the gates on the dam, resulting in a lower water level. Water is being released through a needle valve lower down on the dam. It is risky to lower the water level too fast, because saturated, unstable hillsides could collapse into the dam, clogging the needle valve. Friends of the Eel River has more information on their dam safety page.

The Klamath River Renewal Corporation website provides information about dam removal already in progress on the Klamath River, giving an idea of what the Eel River dam removal might look like. The FERC license surrender order for the removal of the Klamath dams included a recreational plan and a fire management plan for the area after the dams are removed. Keller said according to CalFire, Clear Lake could be used for fire suppression after Lake Pillsbury is gone. Removing Scott and Cape Horn dams will be one of the largest river restorations in the West.

On the issue of who will control water rights to the new diversion water, Keller said nobody on the Russian River side has rights to the water in the Eel. Currently PG&E has rights to this water, which it is allowed to use for power generation and agriculture. Sonoma Water, dependent on the water released by PG&E, says they need this water for their 600,000 customers. Keller said actually, fewer than 600,000 people depend on the Russian River water. Sonoma Water may have 600,000 customers, but not all of them depend on the diverted Eel River water. Currently only 30,000 acre/feet is being diverted annually, half of the historically diverted amount. Keller challenged Sonoma Water to find a way to provide that 30,000 acre feet of water without using the Eel water. Keller said most of the diverted water is used in the Upper Russian River and in Potter Valley. Schneider added that there is no way to tell where the water is used after it leaves Mendocino County.

If you are interested in following this issue, the Russian River Planning Group’s meeting schedule is posted here. Here is a link to the Facebook recording of the Dam Removal Forum.

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  1. California needs all of the dams and reservoirs it has, to be maintained, to provide critical water to all agricultural and household users. The fish need protection from all the illegal diversion of water, dumping of chemicals, human waste and trash. Drought is a danger to all life.

  2. Well hopefully between now and the scheduled dam removal we don’t get a storm like the Christmas storm of 1962! But it would most likely wash the whole basin clean of dam,silt and many down stream properties. Which brings up this question, how dangerous is the current Scott Dam as a result of neglected maintenance?

  3. Such propaganda. The presenters are proponents of removal of Scott Dam. PG&E’s initial draft surrender and decommissioning plan has not been released yet, so the 2028 dam removal target is speculative. No fire mitigation discussions have occurred between PG&E and Lake County, the Lake Pillsbury Alliance or the Lake Pillsbury property owners. They want the public to believe Clear Lake (70 miles away) is an acceptable alternative for fire fighting water. And comparison with the Klamath decommissioning is ridiculous — among other differences, the Klamath has perennial flows and the upper main-stem Eel River and the Rice Fork are known to dry up in late Summer and Fall, in the midst of fire season and leaving no water for RR diversions or to assist ESA fish.

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Monica Huettl
Monica Huettl
Mendocino County Resident, Annoying Horse Girl.

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