A newly released environmental impact statement identifies removal of Hemlock Dam as the preferred alternative for restoring steelhead fish runs in the Wind River drainage.
Hemlock Dam is located on Trout Creek, a tributary to the Wind River approximately 10 miles northwest of Carson.
The dam has been identified as an impediment to the migration and survival of Lower Columbia River steelhead, a fish that is listed as Threatened under the Endangered Species Act.
A final Environmental Impact Statement (FEIS), issued this week by the Mount Adams Ranger District of the Gifford Pinchot National Forest, recommends removing the 70-year-old dam and dredging out a majority of the sediment that has built up behind the dam over the past several decades.
The "preferred alternative" best meets the need to improve fish passage, water quality and habitat conditions in lower Trout Creek.
A final decision on the project -- formally a "Record of Decision" -- is expected in about 30 days.
A public notice announcing the decision will be issued at that time. The FEIS is the culmination of several years of study, which included numerous public comments.
"This has been a thorough and detailed study of a complex situation," said Mount Adams District Ranger Nancy Ryke. "I understand the concerns of those who do not wish to lose some recreation opportunities. However, we are charged with finding answers for threatened species such as the steelhead."
The FEIS analyzed a total of four action alternatives. Two of the alternatives would have kept the dam in place and invested in repairs or upgrades to the existing structure. The other action alternative would have removed the dam, but would have allowed the sediment behind the dam to erode downstream. The preferred alternative proposes to remove the dam and to remove a majority of the sediment from behind the dam to prevent that material from affecting fish and water quality downstream of the project.
The dam was built in 1935 by the CCC to supply electricity for the Wind River Ranger District. A fish ladder was added the next year. The dam later was converted to provide irrigation water for the Wind River Nursery, which closed in 1996. Currently the dam's chief function is providing a
shallow reservoir for recreation.
Trout Creek is thought to have historically produced 20 percent of the steelhead population in the Wind River. In 1998, the Lower Columbia River steelhead, including the Trout Creek run, were listed as Threatened under the Endangered Species Act.
Currently the dam forms a bottleneck to both upstream and downstream swimming fish, and is a barrier to downstream movement of sediment and organic debris. During the summer months, the reservoir behind the dam helps to elevate temperatures in Trout Creek to levels that can be lethal to steelhead.