NEWS

Original culvert that once lay below 67 feet of compacted fill no longer blocks fish passage upstream of Corral Creek.

MOSCOW, Idaho, February 6, 2008 – Federal, State and local efforts are underway to restore Idaho’s threatened steelhead and other fish habitat in one northern Idaho stream.  Up until recently, a 200-foot long deteriorating concrete culvert had barred fish from accessing 18 miles of habitat upstream of Corral Creek.  Partners collaborated to remove the obstructive barrier; now plans are underway to vegetate the stream bank this spring to restore it back to its original state.  

The culvert’s disproportionate size created water pressure too strong for fish passage. “During high spring flows, water would shoot out the downstream end of the undersized culvert approximately 10 to 12 feet before hitting the bank.  This was also the time of year steelhead were migrating to spawn, but could not move further upstream because of the barrier,” said Kevin Traylor, area biologist, USDA Natural Resources Conservation Service (NRCS).  During lower flows, the culvert’s smooth concrete lining dispersed the flow into a thin sheet of water that was too shallow for fish.

NRCS engineers determined an artificial stream channel would be the most viable replacement for the culvert.  They calculated how much water and sediment could come through the stream so it would have the right velocity to allow fish passage, but not erode or degrade. “If we made the channel too small, then water would be too fast, and if the channel was too large, sediment would drop out and fill it,” said Rob Sampson, NRCS state conservation engineer. 

The new stream channel will allow steelhead and other fish to access 18 miles of habitat.

To remove the 200 foot-long culvert, crews had to cut through approximately 67 feet of compacted fill. It took crews 5,000 truckloads to excavate the 49,000 cubic yards of fill above the culvert. Now, a restored stream channel resides in its place, allowing water to flow naturally from the creek to the Potlatch River.

The Latah Soil and Water Conservation District and the Idaho Department of Fish and Game are planning to revegetate the stream bank this spring with native plant species to reduce erosion, enhance stream bank stability and provide shading for the fish. “Plant shade cools the water, which is desirable for fish and the organisms that fish feed on,” said Ronnie Graham, NRCS soil conservation technician. “Planting a healthy riparian zone with suitable vegetation creates aquatic ecosystems that are key to fish survival.”

Additional partners who contributed funding and/or technical assistance for research, engineering, construction, vegetation and/or restoration include the Idaho Department of Lands, Idaho Office of Species Conservation, Idaho Transportation Department, National Oceanic and Atmospheric Administration Fisheries Service and the adjacent landowners.

Please visit www.id.nrcs.usda.gov for additional news releases or information about the USDA NRCS.

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