Surveying the Elwha: A ‘before’ picture of the river
August 19, 2002 - 10:09 a.m. Pacific
ELWHA RIVER, Clallam County — A splash cuts the smooth, jade-green surface of the Elwha River as 20- and 30-pound chinook head upstream. Moments later the river erupts again, this time with the thrashing of dry-suited biologists, snorkeling the river's last free-flowing run.
Scientists from federal agencies and tribes snorkeled the river last week to piece together the first comprehensive survey of the Elwha's fish habitat and populations. They counted juvenile and adult fish, measured the size of rocks and surveyed the lower river's pools, riffles and runs.
The data will be used to create what scientists consider the "before" picture in a grand experiment beginning in 2005, when two dams that have blocked salmon for nearly 100 years are removed.
Taking out both dams is a restoration project without peer: No bigger dams have been removed anywhere.
Surveys will continue throughout the removal and for years afterward to track the river's recovery.
"It's critical to see how the river responds. This is a large-scale experiment, a great opportunity," said Mike McHenry, fish-habitat manager for the Lower Elwha Tribe.
The 105-foot-high Elwha Dam five miles up from the river's mouth was completed in 1913. The 210-foot-high Glines Canyon Dam 13 miles upriver was completed in 1927. The dams were built to generate hydropower to fuel economic development of the Olympic Peninsula.
Over the years they helped power the Navy shipyards at Bremerton, a lumber yard in Port Townsend and a paper mill in Port Angeles. Under the dam-removal agreement, paper-mill owners will receive their power from the city of Port Angeles through the Bonneville Power Administration.
Many regard the Elwha as the best chance for salmon recovery in the Pacific Northwest. The river was home to all five species of Pacific salmon: chinook, coho, pink, chum and sockeye, as well as steelhead.
And its habitat — except for the dams — is pristine, and will remain so. The river's headwaters are the snowmelt of Mount Olympus. About 85 percent of the river the lies within Olympic National Park, protected since 1938.
The dams will be taken out in stages.
Glines Canyon is the easier to tackle. A notch will be cut in its concrete arch a bit at a time, draining the water down until the dam can be removed.
Elwha Dam is more complicated. Tons of concrete were lumped behind the dam to plug leaks when the dam was damaged by a flood in 1912. Cutting a drainage slot into the uneven mass of fill material isn't practical.
Instead, engineers will excavate a river channel in the bedrock to the side of the river. The reservoir will be drained through the diversion, with cofferdams built to control the drawdown during the project.
The river will be restored to its natural channel once the Elwha Dam is down.
Both dams will come out at the same time. The $178 million project is expected to take about two-and-a-half years. No flooding is expected, because the drawdown will be so gradual.
Sediment levels, however, will rocket: An estimated 19 million cubic yards of sand, gravel and rock is impounded in Lake Mills above Glines Canyon Dam.
About half of that will make its way downstream, with the silt moving out of the river system in an estimated two years, the sand in about eight to 10 years, and the rocks rattling downriver over decades.
The project will include pauses in the work to help the water clear when juveniles are moving downriver and the adults are coming back.
To jump-start restoration of salmon runs, scientists for the first 10 years of restoration will also give baby salmon raised from some of the returning adults a deluxe ride via helicopter to the upper river.
The river once produced as many as 390,000 fish, scientists estimate. Today only about 3,000 naturally spawning salmon of all kinds return to the river.
Once home to legendary chinook, the 100-pound June Hogs, the Elwha is just hanging on.
About $600,000 has been spent to restore the lower five miles of the river. Much of the money has gone for engineered logjams, built since 1997 on the river's banks to imitate the deposit of large woody debris the river used to haul and stack on its own.
Juvenile fish rest and feed in the new habitat.
"You never used to see that," said Pat Crain, a biologist for Clallam County. But he still sees a big decline in the river because it is starved for gravel and big wood delivered with natural flows of cold, clean water.
Rivers are living conveyor belts of big logs and wads of roots that lodge along the banks. The knots of debris give salmon a place to hide, rest, feed and stay cool in the shade.
The natural flow of the river also transports tons of sediment and gravel from the upper watershed, used by salmon to build their nests, called redds. If the salmon can't move the material around with their tails, they can't build nests, which is why measuring rocks is an important part of the river surveys.
The two dams in the Elwha River have trapped that sediment and gravel, affecting the shape of the river's banks, mouth and beaches east of its mouth all the way to Ediz Hook in Port Angeles. The Elwha represents an opportunity to restore a functioning river ecosystem all the way from Mount Olympus to saltwater.
It's high time, Crain said: When he began observing the river as a habitat biologist for the Lower Elwha Tribe in 1989, some 7,000 salmon would return to the river.
In recent years, returns have crashed to as low as 700 fish.
Scientists hope that once the dams are out in 2007, runs will recover enough to allow limited fishing within five to 10 years. They predict booming returns by 2027.
Brian Winter, head of the restoration project for the National Park Service, says that with so much pristine, protected habitat to work with, restoration will succeed: "Piece of cake."
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