Success of the restoration project was shown just hours after completion by steelhead coursing down the new channel.
Only hours after water coursed down the new stream channel, the first returning steelhead signified the success of the Hemlock Dam Removal/Trout Creek Restoration project. Hemlock Dam was built in the 1930s for power generation by the Civilian Conservation Corps. It was later retrofitted to provide irrigation storage for the Wind River Nursery, which closed in 1997.
Removal of Hemlock Dam is a study in contrast with the removal of Marmot Dam on the Sandy River in Oregon. Marmot Dam was removed in part by use of explosives, and the sediments behind the dam were eroded away by the river once the dam was gone.
At Hemlock, the dam was torn apart piece-by-piece using heavy equipment. Sediments that had accumulated behind the dam in the past 70 years were largely removed by excavators and large dump trucks. A channel was built in the area that was once a reservoir. The constructed channel is the latest in “green” technology, being built of river rock and approximately 1,000 trees that were pushed over or cut as part of a forest thinning project elsewhere in the watershed.
The new channel is not the only “green” part of the project. Project contractor James Dean of Glenwood, Wash., recycled concrete from the dam for use in other projects. Dean also found a way to replace diesel pumps used to divert the creek on the site with electric pumps, further burnishing the green credentials of the project.
Prior to use of heavy equipment in the reservoir area, the Forest Service along with partner agencies and organizations conducted a three-day effort to remove fish from the project area and were able to capture and relocate nearly 3,000 fish to a safer area for the summer. Once the fish had been removed, the site was dewatered by flipping the switch on 4 large electric pumps, which pumped the entire flow of Trout Creek around the project site through a series of nearly half-mile-long, high density plastic pipes.
As the contractor was excavating sediments from the lower reservoir, a piece of Skamania County logging history was unearthed. The foundation of an old timber-framed splash dam was exhumed, and found to be in nearly mint condition, compliments of being buried by many feet of sediment and water for the past 70-plus years.
The splash dam was once used to temporarily impound water so that it could be released in large pulses to wash timbered logs downstream to the mill. Following initial revelation of the splash dam, it was carefully uncovered, surveyed, and measured by a team of archaeologists along with the Skamania County Youth Forest Success crew, and then removed to make way for the newly restored channel.
A web cam is located on the project site that allowed Web site visitors to view (and even take photos) of work on the project. Visitors to the Web site can actually take control of the Web cam from the comfort of their own chair and can pan across the site, zoom to points of interest and take photos of anything that is particularly interesting. The Web cam is a result of a partnership between the Forest Service and University of Washington’s Canopy Crane program, which is co-located near the project site.
The dam removal and habitat restoration project comes about as a result of funding contributions and support from a wide array of partner organizations and agencies, most notably Bonneville Power Administration, U.S. Fish and Wildlife Service, Salmon Recovery Funding Board, Ecotrust, American Rivers, NOAA Fisheries Restoration Center, Yakama Nation and Mid Columbia Fish Enhancement Group.
Visit the Gifford Pinchot National Forest Web site to access the Web cam: http://www.fs.fed.us/gpnf/04projects/hemlock-dam/removal/. For additional project information please contact Bengt Coffin, Project Manager at (509) 395-3425.