Dam’s removal should boost steelhead trout
Structure quickly ‘outlived its purpose’
TROY, Idaho – A Troy city crew began chiseling away at the long-forsaken Dutch Flat Dam on Wednesday to clear the way for steelhead trout seeking larger bodies of water to spawn in farther north.
Idaho Fish and Game began tagging and tracking steelhead populations in North Idaho about 10 years ago, and found – to the surprise of many – a high density of fish in the west fork of Little Bear Creek in Troy.
“They were making it up to the dam,” said Ken Stinson, Latah Soil and Water Conservation District manager. “They just couldn’t get past the dam.”
With the support of Fish and Game, the district and city of Troy collaborated to demolish the 93-year-old concrete impediment and improve steelhead passage with major funding support provided by the Idaho Office of Species Conservation and Bonneville Power Administration.
“This impoundment, or whatever you want to call it, outlived its purpose by 80-90 years,” Troy Mayor Ken Whitney said. The city provided a crew to run a mounted hydraulic hammer and backhoe Wednesday to knock down the dam. “It just kind of came up in conversations that we had employees qualified to do this stuff.”
Fish and Game employees removed nearly 200 fish in various sizes and stages of development from the upper and lower portions of the creek near the dam last week.
“Anywhere in the construction area, fish are removed and placed downstream, where they’ll be safe from the construction activities,” said Damon Keen, Fish and Game biologist. “We actually found a fair number of fish.”
Steelhead reach the area in March, but have historically been forced to spawn in the limited water the creek provides at the dam. The hope is demolition of the dam and rechanneling the creek into the Potlatch River system will also increase the wild steelhead population, which is currently listed as threatened.
“We have a pretty good spawning habitat up north of here,” said Bob Ries, a biologist with the National Marine Fisheries Service. “We’d certainly get some kind of boost in the population.”
The Fisheries Service provided guidance and options for dam removal, as well as the large accumulation of sediment that settled in almost immediately after the concrete impediment was erected.
Stinson said the lion’s share of work at the Dutch Flat Dam site will be removing about 10,000 cubic yards of sediment. The project is expected to take up to a month to complete.
Once the dam and sediment are removed, Ries said, monitoring will continue with the expectation the steelhead population will spike as it has with other projects to remove blocked waterways.
“We usually find fish getting up there immediately the next year,” he said.
Steelhead are also being blocked in Big Meadow Creek by a culvert running under state Highway 8 in Troy. Fish and Game is collaborating with the state transportation department to replace or modify the existing culvert; however, the project likely won’t be implemented until 2015, Keen said. That will really create a boon for the fish population, said Ryan Banks, senior fisheries technician for Fish and Game.
“All that space you open up, it’s just that much more space for the fish to spawn and the juveniles to rear.”