A Reconnaissance Survey of the Effects of Sediment Traps on Michigan Streams

Abstract

AbstractExcess sand bedload can significantly degrade salmonid habitat and populations. Successful use of sediment traps to restore habitat and salmonid populations on two Michigan streams in the early 1980s led to application of traps at well over 100 coldwater streams in Michigan and rivers throughout the USA within a decade. Unfortunately, little quantitative evaluation has occurred other than anecdotal observations for some traps. We conducted a broad‐scale survey of 65 Michigan stream reaches with sediment traps by collecting data along transects upstream and downstream of the traps to assess downstream changes in substrate composition, channel depth, and channel stability in response to sediment traps. We found that recent applications of sediment traps (usually as stand‐alone instream habitat treatments) had no significant effect on substrate, thalweg depth, or bank stability conditions in the reaches studied. Using reach‐based estimates of specific stream power at the 10% annual exceedence flow, we identified areas where sediment traps could potentially destabilize channels. Specific stream power estimates were positively correlated with the preponderance of gravel and coarser substrate in stream reaches. Our study and previous assessments of sediment traps suggest that managers carefully consider their river and all potential management options when deciding if sediment traps will provide the best return on their investment.Received April 12, 2012; accepted July 4, 2012