PORT ANGELES, Wash. — At the lower Elwha Dam, backhoes move massive mounds of dirt from one side of the riverbed to the other. They’re diverting the river temporarily, so the dam can be taken apart, layer by layer.
An immense amount of sediment has built up above the dams –- enough sand and dirt to fill 23 Empire State Buildings.
The Elwha foams and churns – like angry chocolate milk - thick and brown with sediment.
As more sediment is released, scientists want to understand how it will change the river and the creatures that live here.
A few miles downstream from the dam, a team from the U.S. Geological Survey stands on a bridge getting ready to lower what looks like a two-foot-long model submarine into the river 60 feet below.
“I gotta be honest. I spray-painted this before we came out here to make it look a little prettier,” says James Foreman, a scientist with the USGS, as he hits the button on the electric pulley. This releases what’s called an isokinetic sampler off the side of the bridge. It looks like a World War II submarine — its smooth lines make it perfect for lowering into flowing rivers to collect water samples. This old tank was used to measure how much dirt and mud made it into nearby rivers after Mount St. Helens erupted in 1980.
And more than 30 years later, its job is the same. The USGS is using it to monitor how much sediment is moving out of the two reservoirs above the dams and where it’s going. [[Here’s a link to the USGS report about the state of the Elwha River prior to dam removal.](http://pubs.usgs.gov/sir/2011/5120/ “”)]
The sediment being released from above the dams will change the shape of the river and create a healthier delta with more spawning grounds for salmon.
View Elwha River Dams in a larger map
Chris Magirl, another researcher with the USGS, stands on the bridge waiting as the sampling device comes up.
“Sediment’s important to the river in how the river moves around,” Magirl explains. “Sediment is also important to the fish. If you have too much sediment it’s hard on the fish so there’s a balance there.”
Too much sediment in the water and fish can’t feed.
Right now, there’s a lot more sediment in the Elwha River than there was before dam removal began.
And that has some biologists worried about what will happen to the coho, chinook and other salmon that try to repopulate the river. But so far, things are looking pretty good.
John McMillan, a biologist with the National Oceanic and Atmospheric Administration, stands in a sheltered side channel of the Elwha not far from Magirl and the USGS team.
This spot has been protected from all the dirt and sediment coming down the main river from above the dam. McMillan says salmon are already taking advantage of these safe havens.
“Fish find habitat that they can survive in and make the best of it,” he says.
McMillan points into the water nearby. It’s hard to see, but down in the gravel on the river bottom, a coho salmon has dug out a nest and laid eggs.
“These are the first coho that are actually going to have a chance, their offspring can hopefully come back up when there’s no dam.” McMillan’s eyes light up like a little boy’s. “It’s their first shot at it, it should be fun to see.”
McMillan and biologists with the Lower Elwha Klallam tribe have found almost 100 other egg sacks like this one in the Elwha and her tributaries.
These eggs were laid by coho from the tribal hatchery near the mouth of the river, but they are descended from native Elwha coho salmon. This winter hundreds of adult hatchery coho were transported above the first dam. [Here’s a [link to the video](“”) of the transport.]
Mike McHenry, a biologist with the Lower Elwha Klallam tribe, says even though the parents of these eggs are from the hatchery, the offspring will grow up wild.
“For all practical purposes they will be living in natural habitats and adapting and being subjected to natural selection and doing their thing,” he says. “It’s game on. We’re into recolonization now.”
These coho eggs will hatch in early spring. The young will hang out in the river for about 18 months and then head to the ocean. By the time they come back, the dams will be gone.
Fishing will be closed for the next five years to allow time for the sediment to wash downriver and the fish to return.
Dam removal has continued through the recent snowy weather. For the latest updates on the dam deconstruction process, visit the Olympic Park’s Elwha blog.
(Text and audio by Ashley Ahearn. Video and still photographs by Katie Campbell.)