By Rob Ollikainen
Peninsula Daily News
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Andy Ritchie, Olympic National Park hydrologist for the Elwha River restoration project, will share his experience of monitoring and managing sediment flow on the Elwha in a public presentation Tuesday.
The free program will begin at 7 p.m. at the Olympic National Park Visitor Center, 3002 Mount Angeles Road in Port Angeles.
Peninsula Daily News
The probe collected samples of suspended sediment from one of the world’s most-studied petri dishes.
Mark Mastin, surface-water hydrologist for the U.S. Geological Survey in Tacoma, said the samples were sent to a USGS lab in Vancouver, Wash., for analysis.
The samples will be calibrated with the stationary water turbidity meters on the now-free-flowing river for a continuous record of the Elwha’s sediment load.
Murky sediment is racing down the river because the dams that constricted its natural path for nearly a century are essentially gone for the first rainy season.
Contractors removed the last remnants of Elwha Dam, which stood for nearly 100 years west of Port Angeles and 5 miles from the river mouth, in March.
Glines Canyon Dam 9 miles upstream in Olympic National Park has been lowered to the bottom of its former reservoir and is scheduled to be fully gone in May.
Scientists say the two dams blocked 25 million cubic yards of sand, silt, cobble and gravel in the Lake Aldwell and Lake Mills reservoirs behind the dams.
“The big issue with removing the dams is how much sediment is going to come out and where it’s going to go,” Mastin said.
Twenty-five million cubic yards is enough sediment to fill the length of a football field to the height of 11 Empire State Buildings.
Dam removal is the cornerstone of the National Park Service’s $325 million river and salmon restoration effort, the largest of its kind in U.S. history.
“It’s pretty exciting,” Mastin said.
The scientific community is focused on the ever-changing river, especially now that sediment is pouring over the top of Glines Canyon Dam and the river is running high amid seasonal rains.
State and federal agencies and the Lower Elwha Klallam tribe are monitoring the effects of the sediment on fish and changes to the physical properties of the lower river and near-shore zone.
Olympic National Park spokeswoman Barb Maynes said fewer salmon are being collected at the tribal fish hatchery, but it’s too soon to tell how fish are responding to the sediment.
John Clemens, USGS spokesman with the Washington Water Science Center in Tacoma, said 4.5 percent of the sediment trapped behind the dams already has moved downstream.
Mastin and hydrological technician Greg Justin were tracking that movement by sampling water from the Clallam County bridge not far downstream from the Elwha Dam site.
The USGS also collects suspended sediment samples from the Altair area below the once-210-foot Glines Canyon Dam.
Before Glines Canyon Dam was lowered to the bottom of Lake Mills, about 90 percent of the sediment flowing down the river was fine silt.
Mastin said the sediment composition has become 50 percent coarser.
“We’re seeing a lot more sand coming down the river,” he said.
“We don’t have a good handle on exactly how much, but we’ve seen it upstream.”
Flows have risen sharply within the past 1½ weeks — from about 2,000 cubic feet per second, or cfs, at the USGS gauging station at the McDonald Creek bridge to about 4,000 cfs Friday.
Flows spiked at about 7,000 cfs early last week.
The USGS likes to collect suspended sediment samples when flows are high and churning.
“It’s sort of event-driven,” Mastin said.
“The most important action occurs when flows increase and rise.”
More than half of the sediment stuck behind the dams will remain in the reservoir beds, destined to be covered with vegetation.
Turbidity, measured in formazin nephelometric units, or FNU, has spiked dramatically since the summer.
The haze gauge was fewer than 500 FNU in the dry months. It rose to nearly 1,600 FNU early last week.
Also last week, sediment and woody debris moving down the river clogged filters at the Elwha Water Treatment Plant.
The plant supplies water to the Lower Elwha Klallam hatchery, the state Department of Fish and Wildlife rearing channel and the Nippon Paper Industries USA Inc. mill in Port Angeles.
A team of consultants and engineers was on-site Monday and Tuesday to modify the intake system.
Maynes on Friday said the problem is being addressed and that the plant continues to produce clean water.
In other project news, park spokeswoman Rainey McKenna said revegetation crews have completed seeding and planting operations for the year.
In October and November, Olympic National Park staff, Washington Conservation Corps crews, the Lower Elwha Klallam tribe and a team of volunteers planted 32 acres with 16,800 seedlings in the drained reservoirs.
All told, more than 46,000 seedlings have been planted since the project began, McKenna said.
Reporter Rob Ollikainen can be reached at 360-452-2345, ext. 5072, or at email@example.com.