Salmon Trout River Bridge: Soft Armor and SRBs Protect Coaster Brook Trout Habitat

Michigan DEQ asked the Marquette County Road Commission to bring APS into erosion and sedimentation planning for a Triple A Road bridge over a stream that drains to the Salmon Trout River in the Upper Peninsula. A citizen complaint had flagged construction damage and sedimentation in nearby streams and wetlands. The Yellow Dog Plains are remote and pristine; the Salmon Trout holds the last remaining south-shore Lake Superior run of native coaster brook trout—the largest surviving form of brook trout in that range.

Initial BMPs were only rocks and hay bales. APS designed polymer-enhanced soft armoring and sediment retention barriers (SRBs). All slopes draining to the stream received APS 712 Silt Stop® powder on open-weave matting (jute, coir, or similar)—binding soil against wind and water erosion and supporting vegetation after disturbance. Hydroseeding can include the polymer in the seed mix. Auburn University research cited in the case study reports polymer-enhanced soft armoring can be 100% effective at preventing soil loss and sedimentation when properly applied.

At the toe of slopes, SRBsdouble rows of Georgia Type C silt fence about 4–6 feet apart, filled with mulch or organics blended with 712 powder—trapped fines that ordinary silt fence misses. Sediment stayed on site; the stream was not impacted during bridge construction. The finished crossing protected coaster habitat while the Triple A Road upgrade for logging, recreation, and Eagle Mine haul traffic continued.