A Long‐Term Analysis of Channel Morphology and Stream Substrates before and after Sediment Trap Construction in Michigan Trout Streams

Abstract

AbstractSediment traps are commonly used to remove excess sand bedload from coldwater streams and to improve channel morphology and substrate conditions for salmonids in the Midwestern United States. However, few scientific evaluations of the rate and spatial extent of channel changes associated with sediment trapping efforts have occurred. We used a series of stream channel morphology measurements taken over a 10‐year period in five Michigan streams to show that excavation of sediment traps had only small effects on mean channel bank‐full depth, bank‐full cross‐sectional area, and bank‐full width as well as substrate composition in the streams studied. When they did occur, changes in each of these metrics occurred both upstream and downstream of—and often in close proximity to—the sediment traps. While few positive effects of sediment traps were noted, there were also no negative effects to report. The construction of sediment traps did not lead to broad‐scale widening of stream channels, and no excessive channel incision was observed in any of the study streams. Thus, concerns about typical sediment trap operations upsetting the stream‐sediment equilibrium and creating excessive down‐cutting appear to be unfounded for Michigan's low‐gradient, naturally sandy stream channels. We conclude that sediment traps are unlikely to have any large‐scale channel morphology or substrate effects that would be beneficial to stream salmonids when used as a stand‐alone habitat treatment.