Hemlock Dam removal one year later

Trout Creek flows freely after 100 years.
Trout Creek flows freely after 100 years.

The roar of rushing water makes conversation difficult as you cross the bridge over Trout Creek in Washington’s Gifford Pinchot National Forest. The creek – really more of a river – burbles over boulders and stones. It winds its way past banks scattered with tiny native saplings and shrubs. Birds skim the water and rest on tall grasses along the banks.

What isn’t immediately obvious is that one year ago, this entire scene was under water. The dramatic change in the area is due to a Bonneville Power Administration-funded U.S. Forest Service project that removed Hemlock Dam and reconstructed Trout Creek to a natural state. The $2.7 million project made an immediate difference for the fish: hours after the dam was removed and the stream was re-watered, an adult steelhead was seen making its way upstream.

Hemlock Dam was originally constructed in the 1930s. Over the years it generated hydropower and later provided irrigation water, but stopped serving any purpose in 1997. The 26-foot high concrete dam not only blocked fish on their migration up the creek, but also created a shallow reservoir, flooding the area with several feet of water that heated up in the sun to temperatures above what the fish could bear.

The U.S. Forest Service declared the dam the main limiting factor in recovering endangered wild steelhead in the area, so BPA, in coordination with the Northwest Power and Conservation Council, stepped forward in 2007 to help fund the removal of the dam and reconstruction of the creek. “BPA’s support was critical to the success of this project,” said the Forest Service’s Bengt Coffin. “Once they signed on, many other agencies stepped forward to lend their support as well.”

One year ago in July, removal of the dam began. Biologists carefully relocated all the fish from the creek before a massive pump drained the water and piped it around the dam site. Then, heavy equipment worked from dawn till dark to remove the concrete dam and chunks of a logging dam dating back to the turn of the century. Engineers dug out a sinuous channel and created an in-stream island that serves as a flood plain. Crews anchored the island with huge logs and snags salvaged from the old dam. They used natural materials like gravel and rocks, rather than the usual metal cables, to anchor the logs in place.

The creek bed was lined with rocks and stones specifically sorted by size to attract spawning steelhead. A wetland was created nearby to replace wetlands that had grown up around the reservoir. Thousands of native plants were planted to provide shade to the creek and stabilize its banks.

Since 2005, BPA has funded projects that have opened up more than 1,000 miles of habitat for fish by removing obsolete diversions, dams, mine tailings and other barriers. “BPA is committed to protecting and improving the environment for fish and wildlife in the Pacific Northwest,” says Bill Maslen of BPA’s Fish and Wildlife Division. “This project is a great example of the painstaking science behind our efforts to protect and enhance habitat for fish. In this case, dam removal made perfect sense.”

The Hemlock Dam Removal project was also supported by the U.S. Forest Service, Salmon Recovery Funding Board, the Yakama Nation, U.S. Fish and Wildlife Service, Ecotrust, Mid Columbia Fisheries Enhancement Group, NOAA Fisheries and American Rivers.

Source: bpa.gov