Friends of the Eel: PG&E Admits Scott Dam Faces Serious Seismic Risks

Friends of the Eel River: PG&E Admits Scott Dam Faces Serious Seismic Risks

WWW: Eel River diversions play a major role in keeping water running year-round to the Russian River. Anything that happens on the Eel has big impacts on Sonoma County.

Greetings Friends,
Have you heard the latest news from PG&E? The company appears to be finally taking dam safety seriously! In a press statement published last week, PG&E announced that due to new information and updated seismic analysis, they will never again close the gates on top of Scott Dam. This will permanently reduce the Lake Pillsbury reservoir capacity by about 20,000 acre feet. The company says they made this decision “out of an abundance of caution in the interest of community safety”. I love this part – we told you so, PG&E!

Click here to read our press release and access our trove of documents on dam safety, and see below for additional details.

In other news, Northern California summer steelhead were featured in Sierra magazine this month. Eel River dam removal remains the best chance at a future for these critically endangered fish. As biologist and summer steelhead expert Samantha Kannry puts it, “summer steelhead are on the verge of extirpation, and most people don’t even know they’re here”.d to connecting with you!

PG&E Admits Scott Dam Faces Serious Seismic Risks

As mentioned above, PG&E announced last week that they will never again close the gates on top of Scott Dam. This will permanently reduce the Lake Pillsbury reservoir capacity by about 20,000 acre feet. The company says they made this decision “out of an abundance of caution in the interest of community safety”.

In a filing to the Federal Energy Regulatory Commission a few days later, PG&E explained that a March 14 memo from their engineering consultants Gannett Fleming, Inc is what prompted this sudden action to reduce the volume of water in the reservoir. The referenced memo is, of course, classified as Critical Energy Infrastructure Information (CEII) and not available to the public, but it’s clear that the contents of that memo startled the company enough to prompt immediate action.

Friends of the Eel River has been focused on the questionable dam safety analysis at the Potter Valley Project for years. We’ve even gone so far as to publicly question whether PG&E is concealing dam safety liabilities.

Analysis of the San Andreas Fault system by the USGS reveals that the Bartlett Springs Fault, one of three major structures in the system, is capable of producing up to a magnitude 7 earthquake. We also know, from a study we commissioned by Miller Pacific Engineering in 2018, that the active landslide adjacent to the south abutment of Scott Dam presents significant geologic hazard to the dam.

And of course, we can’t forget about the unusual construction of Scott Dam. As we outlined in one of our dam safety blogs two years ago, Scott Dam had to be redesigned mid-construction to accommodate a large unstable boulder that was originally thought to be bedrock. This boulder, named “the knocker”, now sits just behind the dam near the sharp angle that resulted from the seat-of-the-pants redesign back in 1920. Without more transparency from PG&E, we are left wondering whether that design change resulted in a weaker structure.

This reduction in reservoir capacity may make it more challenging for PG&E to maintain temperatures appropriate for salmon and steelhead. However, thanks to our pending Endangered Species Act litigation against PG&E and FERC, both entities are on notice that continued harms to Eel River fish will not be tolerated. We have reason to believe that the National Marine Fisheries Service will once again be firm that PG&E must maintain at least a 30,000 acre foot pool of cold water in the reservoir to ensure that downstream releases are cold enough for native fish to survive.

Further reading here.

Upcoming Events

What: Friends of the Eel River Open House
When: Wednesday, March 29 from 5 to 8 PM
Where: Synapsis (1675 Union Street, Eureka, CA)