Wood restoration results in rapid conversion of a degraded plane‐bed channel, Little River, Washington

Abstract The loss of instream wood can create a legacy of channel incision that is detrimental to habitat formation. In Pacific Northwest streams, wood restoration is often the primary tool to recover spawning and rearing habitat for Pacific salmon. An incising mountain stream on the Olympic Peninsula, Washington, was evaluated for its response to wood restoration using geomorphic and habitat parameters. Incision processes were related to historical wood clearing and downstream dam removal. Wood restoration rapidly reversed or reduced location‐dependent channel incision rates. Three years following wood insertions, we measured geomorphic and habitat responses and channel topographic changes. Placed wood was stable, and no significant movement was observed. Pool abundance increased by 68% following restoration. In the lower reaches, topographic surveys show a channel incision decline from 2.0 to 0.5 m/year, whereas the upper reaches had an incision reversal and net aggradation, particularly upstream of logjams. Wood restoration significantly affected sediment characteristics; D 50 and D 90 grain sizes were reduced by 76% and 143%, respectively. We discuss how habitat response may affect the recovery of Pacific salmon and lamprey populations.