Restoration Considerations of Large Woody Debris in the Elwha River Nearshore, Olympic Peninsula, Washington

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Large Woody Debris (LWD) is a critical component of Pacific Northwest marine ecosystems and of growing interest for restoration. This study adds important empirical data to the limited pool of information on the dynamics of LWD at the interface of freshwater, human, and marine ecosystems. In Washington State, the Elwha River nearshore is significantly ecologically altered due to shoreline armoring and upstream dams. The Elwha dam removal project, begun September 2011, is anticipated to change the composition, delivery rate and volume of LWD. We describe baseline characteristics of LWD in the Elwha River’s drift cell relative to unaltered areas with intact hydrodynamic processes by landform type, discuss anticipated changes, and consider the need for future work to understand and promote LWD in this restoration event. Results indicate LWD volumes of the Elwha nearshore were significantly lower than certain comparison areas; average site volume on Elwha’s spit was 0.83 m³ versus 18.6 m³ of the comparison spit. Similarly, the average number of pinned and buried LWD pieces (0.5 vs. 13.7) and count of straight logs (6.5 vs. 36.5) (composition) were significantly lower than those in the comparison spit. Current lower volume and differing structure of LWD likely contributes to impairment of ecological functions in Elwha’s nearshore. While dam removals may result in partial restoration of nearshore processes, ongoing decreased wood recruitment attributable to early logging, harvesting, and shoreline armoring are likely to continue preventing LWD accumulation. Restoration efforts should prioritize actions such as the removal of armoring and reduction of wood harvest.