By: Contech Bridge Solutions
The Manistee River in Manistee County, Mich., has seen decades of fluctuation in its fish varieties and populations. Several species have disappeared entirely from the watershed largely as a result of habitat destruction and degradation of the streambed due to human activity. Over 70 species of fish currently make up the Manistee’s native fish community, with the continued survival of some, like the lake herring and lake sturgeon, severely threatened.
Those with a vested interest in the watershed range from small local governments to large federal bureaucracies. Organized local fishing and hunting groups and recreational groups from 67 townships and 18 cities, villages and towns in Michigan have all made efforts in protecting and preserving the river and the fish species that inhabit its waters.
With ongoing bank stabilization projects along the river and its tributaries, many stream crossings are evaluated based on hydrology, potential sediment delivery and fish/aquatic organism passage. In the Huron-Manistee National Forests in Michigan, the United States Forest Service (USFS), along with the Conservation Resource Alliance (CRA), selected a site at Sickle Creek for a critical culvert replacement.
“The existing culverts were small, short and did not easily allow fish to pass upstream,” said Mark Johnson of the CRA. “All of those issues are addressed with an arch culvert.”
The replacement structure, a CON/SPAN Bridge System with a 16-ft clear span, replaced two 36-in. CMP culverts. Existing deficient culverts such as these can be detrimental to the fish that need to migrate up- or downstream for survival. The culverts can create high water velocities and thus an upstream migration barrier that most fish cannot navigate. They also are often the cause of debris and sediment buildup in the piping or upstream opening.
The installation of the bottomless precast concrete arch structure by the Premarc Corp. marked the largest stream-crossing project for the USFS. The new arch structure opened up a half-mile of stream for fish and organism passage and improved hydrology of the stream. The clear span, with the use of a strip-footing foundation, provides a natural habitat corridor for the resident brown trout as well as trout and salmon migrating up- and downstream.
