Anna River Culvert Replacement: Polymer-Enhanced BMPs Protect a Michigan Salmon Stream

The Anna River culvert replacement project on Perch Lake Road in Alger County, Michigan, had to keep a sensitive Upper Peninsula salmon stream clear while replacing a failing metal culvert with a concrete box culvert. The Anna River runs 7.1 miles southeast of Munising; Perch Lake Road is the only access for lakeside homeowners and local logging. With excavation, sheet-pile diversion, and limestone bedding in the channel, sediment and turbidity were inevitable—so the Alger County Conservation District brought in Applied Polymer Systems (APS) to design polymer-enhanced best management practices under Michigan’s Rule 97 permit for polymer use in state waters. See APS’s sediment control enhancement approach.

APS deployed a layered passive treatment and stabilization package. Eight APS Floc Logs and jute particle curtains were installed 20–30 feet downstream to flocculate and capture fine sediment before it could move into the river. Upstream of the work zone, a diversion channel isolated the old culvert; limestone lining was treated with APS Silt Stop® powder so white lime plumes would not travel downstream. Bedding material, crushed limestone, road-to-stream slopes, and all disturbed soils (except the finished road surface) received polymer powder—often blended with seed and fertilizerthen soft armoring with polymer-enhanced mulch and matting. Polymer-enhanced rock checks protected ditch lines and supported erosion control.

Results were visible on site. Within minutes of opening the diversion, small salmon were swimming in clear water; adult spawning salmon continued upstream through the diversion while the new box culvert was assembled. The project finished in five days. Floc Logs were removed at completion; jute curtains were left on the forest floor to decompose. After a snow event days later and through spring breakup, soft armoring held—no erosion, sediment loss, rills, or gullies. One year later, vegetation was established and clear water still ran downstream, with no impacts to the salmon run during construction.