Thursday, July 29, 2010

Habitat improvements in the wake of a dam removal

Last month I got outside and saw first-hand how stream habitat can begin to change following the removal of a dam. Hemlock dam, built in 1937 on Trout Creek in the Wind River watershed, was initially constructed to provide power and water to the Civilian Conservation Corps and Forest Service. Trout Creek provides critical habitat for Lower Columbia River steelhead, listed as threatened under the Endangered Species Act, but the dam (even with a fish ladder) effectively blocked fish passage to spawning grounds and degraded habitat for fish downstream by increasing water temperatures in the creek.

Hemlock Dam, 2006 (photo by USFS)

In the 1990's, several federal and partner agencies decided that the creek should be restored and the dam removed to benefit the steelhead and other native fish in the community. The Fish Passage Program under the Fish and Wildlife Service contributed approximately $250,000 along with funds from partners totaling $2.1 million, and in the summer of 2009, action finally took place: the pump house was removed, the creek was diverted, Hemlock dam was dismantled, the creek channel was reconstructed, invasive weeds were removed, and riparian habitat was enhanced with native shrubs and trees.

Today, one year later, you can see the benefits of the dam removal project. Most notably, Hemlock Lake is no longer there! In its place is a meandering creek channel, with small trees planted on the banks that were previously under water. It will take time for the trees and brush to fill in, but in the meantime, the restored section of Trout Creek has likely been recolonized with lotic aquatic insects for fish to eat, sediment that had built up behind the dam over the years has been removed, and temperatures are no longer near the lethal limit for fish. Additionally, removing this barrier has opened upstream habitat for spawning and migrating steelhead.

Hemlock Lake, 2006 (photo by USFS)

The same view as above in June 2010, only it's now Trout Creek instead of Hemlock Lake! (photo by Donna Allard, USFWS)

With this improvement to Trout Creek, I'm looking forward to seeing how the habitat changes in the project area in the years to come. Be sure to take a look at the Forest Service's website about the project - it even has a video of an adult steelhead that moved up through the project area just hours after flow was restored through the creek bed! The video also shows a tractor moving large woody debris into the floodplain of the stream to enhance fish habitat...word gets out fast among the fish, it appears!

1 comment:

  1. what blarney. the lake was a beautiful site for families to have picnic and for kids to learn to swim. your blarney about the threat to fish from the dam developed decades after the dam should have had its allegedly negative impact.

    what folly.