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Forest Service Tunnel, Sediment Dam Concerns Raised; County Told Failure Could Flood Downstream Communities
Summary
Commissioners heard that core samples at a tunnel and sediment dam near Silver Lake showed poor soils (ash) and that Forest Service options will be expensive; staff warned a failure could produce catastrophic downstream flooding.
County officials summarized recent technical work and Forest Service planning on a tunnel and sediment dam near Silver Lake that helps protect an older dam and downstream communities.
Officials said the Forest Service took core samples and found ash deposits that do not provide a good foundation for permanent structures, and that the Forest Service will present several high‑cost options. The Army Corps has declined to take ownership of the problem, county staff said, leaving the Forest Service responsible for recommendations and potential work.
“If that thing washes out, you got, they said, like, a Mount Saint Helens coming down that river again,” one county official recounted from meetings. Staff told commissioners that emergency management has discussed the risk and that a failure could put 14 feet of water into downstream communities in a severe event.
County staff said the tunnel and dam are large, expensive problems and that the Forest Service will present options; they noted the technical and funding complexity and that long‑term solutions will require coordinated engineering and likely substantial funding.
No county commitment to financing was made; staff said they will follow the Forest Service recommendations and continue to monitor engineering reports and emergency management planning.
