Saturday, July 28, 2012

Largest Dam Removal In U.S. History, Fish Returning To Elwha River

In September 2011, the largest dam removal in U.S. history began on the Elwha River in Washington—home to all five species of Pacific salmon. Just a few short months after the 108-foot tall Elwha Dam was removed, fish are already returning to their restored habitat.

Part of the restoration process was releasing tagged fish into the river above the lower dam to jump start the recolonization of the high quality habitat that had been cut off from migratory salmon for almost a hundred years. So far we’ve released about 60 steelhead and 600 salmon into the river upstream of the former dam site. These fish are even spawning already.

First wild steelhead radio tagged in the Elwha River after the dam removal. 
Credit:: NOAA

The return of wild, un-tagged fish—that found their own way up the river without our help—means that they sense that the river is open again. While out monitoring the river, NOAA scientists spotted several un-tagged steelhead. One was a robust 35 inches, bigger than any of the fish tagged and released.

Steelhead are already spawning in the newly opened Elwha River. The top fish with the red lateral line is the male. 
Credit: NOAA

This is encouraging news for the Elwha and for other dam removals nationwide. It confirms what we suspected: that once the barrier is gone, fish can recolonize the river without assistance and at a faster pace than we anticipated. In March 2012, the Glines Canyon Dam, located eight miles upriver from the former Elwha Dam site, was removed.

Watch the video below to learn more about the science behind restoring the Elwha River watershed and salmon populations. This large-scale restoration takes collaborative effort through habitat construction and scientific analysis to measure the response of fish populations to the dam removals.

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