September 22, 2021 | By:

10 Year Anniversary of the Elwha Dam Removal Project

Update from Anne Shaffer, PhD of the Coastal Watershed Institute on tracking Elwha nearshore ecosystem restoration post-dam removal. 

This month marks the 10 year anniversary of the Elwha dam removal project. The majority of dam removal sediment was predicted to be delivered to the coastal zone within five years of dam removal. This delivery, combined with ecosystem scale shoreline restoration, resulted in dramatic changes to the Elwha delta and shoreline that started almost immediately after dam removals began. Now, 10 years after the project started, the gift of 100 years of sediment has been delivered, and Elwha coastal zone transitions into a ‘post restoration’ phase that includes continued habitat transformations driven by complex seasonal changes in hydrodynamic processes.

And fish use? Our decades of monitoring of the nearshore has documented that surf smelt spawning has expanded across the drift cell, and while newly formed nearshore delta habitat was used immediately, it’s the original, well established and enduring original west delta nearshore habitat, and specifically the constrained west lower river side channel/estuary that continues to provide consistent and important, and now year-round refuge for juvenile coho and Chinook.

According to the senior Olympic National Park (ONP) biologists, only chum and pink numbers are not increasing, and continue to be in very low numbers in the watershed, indicating that 10 years after dam removal, ecosystem recovery is still not complete. These ONP observations are consistent with our findings in the nearshore where our decade of monitoring shows a persistent low out-migrating pink numbers and a troubling decreasing trend in juvenile chum. Our observations indicate that hatchery practices may be playing a role in suppressing pink and chum recovery and need to be modified to allow chum and pink, once the backbone of the Elwha ecosystem, to recover.

It’s been a very challenging and rewarding decade. We once again say a heart-felt thank you to our hard-working, talented, and good-willed team of staff, collaborators, and supporters. With them CWI’s dedication to hard but necessary work, and learning, continues.

Click here to explore a recent 360-degree view of the Elwha nearshore.

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