Silt from Elwha River dam removal doesn't hang around, say scientists

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by GARY CHITTIM / KING 5 News

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KING5.com

Posted on July 26, 2012 at 4:44 PM

Updated Thursday, Jul 26 at 8:14 PM

Before the historic removal of two dams on the Elwha River, scientists studied all the plant and animal species they could. They wanted to know how a giant plume of silt from the removal project would affect them. Scientists returned to the Elwha Thursday to find out.

PORT ANGELES -- As EPA diver Sean Sheldrake prepares to step into the sediment-filled Strait of Juan de Fuca, he knows the risks that await him.
 
"Now that the dams have been removed, there is no more 50 feet of horizontal visibility. It's really where the rubber meets the road, as far as this study and dam's removal,” said Sheldrake, whose team is assisting divers and scientists from the U.S. Geological Survey. "We're going to stay close together."
 
Sheldrake was also here last year helping the USGS explore and document the bottom of the strait where the Elwha River flows out. Since then, the dam removal has sent a massive plume of silt downriver and into the strait. The USGS has spent years studying the area so it can compare and contrast the ecosystem before and after the dam removal.
 
After 40 minutes under the 45 degree temperature water, the dive team surfaces with video and a surprise. They say the thick cloud of silt is there, but it seems to be floating above the sea floor and is being whisked away by the heavy currents.
 
USGS research ecologist Jeffrey Duda said early indications are the ecosystem is naturally designed to handle this type to event and it bodes well for the the months and years ahead as the Elwha returns to a free flowing river.

He warns heavier sediment will flow down the river later, but for now, the largest dam removal project in U.S. history is not causing the kind of damage many experts expected.
 

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