MWC Project Compliments Culvert Replacement

Restoring Fish Passages On Small Streams

Trout and other stream-dwelling fish are notorious for hanging around favorite pools and riffles.  Individual fish will set up for several weeks in holes with good over-head cover, and even defend feeding zones.  But over the course of a year, fish need to move up and down the watercourse seeking new microhabitats when flow, temperature and other conditions change.  Trout need to reach spawning habitats where gravel is washed clean, and may migrate to the mouths of cool tributaries and springs when the water warms in late summer.  

Among the most detrimental obstacles to fish movement in streams are perched culverts set too high during road construction.  They make it difficult, if not impossible, for fish to move upstream, especially during low flow periods.  Perched culverts also can impound fairly large areas, contributing to stream warming and sedimentation.  Some encourage beavers to build more and bigger impoundments.  

Thanks to increased availability of federal funds for “aquatic-organism passage” more culverts are being reconstructed.  One such project occurred recently on Big Murphy Creek on Hiawatha National Forest land in Schoolcraft County.  There, the U.S. Forest Service removed a key culvert as part of habitat improvement work to benefit brook trout.  In 2010, the Forest Service will team with the Michigan Wildlife Conservancy to improve a 2,000-foot stretch of Bear Creek, a tributary to Big Murphy Creek.  The work is less than a mile upstream of the culvert re-construction, which has greatly increased passage of brook trout, especially juveniles.  

In 2006, in a small stretch of Bear Creek, installation of log bank covers narrowed and deepened the stream, speeded the current and restored overhead cover.  Electrofishing one year before installation and three years after installation revealed that numbers of brook trout 6-9 inches in length doubled despite moderate fishing pressure.  Brook trout reproduction remained high.  The initial project created more pool habitat and overhead cover in what had been a shallow, wide channel.  Average channel width decreased to about 50% of pre-project width.  So, the joint Forest Service – Michigan Wildlife Conservancy project in summer of 2010 is expected to have great impact—greatly expanding this work and enhancing benefits from the culvert re-construction.  

Perched culverts are under scrutiny in the Lower Peninsula as well.  Federal funds will likely be used in Oceana County to replace culverts on the White River and several of its tributaries.  Several of those culverts are as old as 40 years.  Some are just 12-14 inch diameter pipes, but at some road crossings there are two or three larger diameter perched culverts.  So, projects can become quite expensive.  

“This type of work benefits all stream fish and a variety of other wildlife,” says Chuck Bassett, a biologist who oversees Forest Service fish projects in the Central Upper Peninsula.  “It’s not just about salmon, steelhead and other anadromons species that migrate from the Great Lakes.”

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