PORT ANGELES — Formed by coastal erosion and Elwha River sediment, Ediz Hook is among the North Olympic Peninsula’s most iconic geographic features, a three-mile, heavily visited spit just a mile from downtown.
The Hook created one of the deepest harbors on the West Coast, is home to Coast Guard Air Station/Sector Field Office Port Angeles and, until the 1930s, was also home to Klallam tribal members.
But the Hook is getting hungry.
After nearly 100 years of river blockage by two dams, sediment flow from the river’s mouth to the hook has been reduced by 35 percent, according to the U.S. Army Corps of Engineers, which said the Hook is eroding at a rate of 4 to 5 feet a year.
So the agency is doing something about it, even as the beginning of the end looms for two dams on the Elwha River that have been holding back between 21 million and 28 million cubic yards of sediment.
The dams will be torn down beginning in two weeks in the largest dam removal project in the nation’s history, a $325 million, three-year affair.
The Corps is seeking bids, with the period closing Sept. 16 — a day before ceremonies and celebration in Port Angeles mark the dams’ demise — to “renourish” the Hook in a project estimated to cost between $500,000 and $1 million.
The sediment released by the removal of the Glines Canyon and Elwha dams is expected to not only help restore the river’s sorely depleted salmon habitat, but also re-coat the Hook, the Bureau of Reclamation said in May when it revised its earlier estimates upward by 2 million cubic yards.
But because the rate of sediment flow is unknown, the Corps will proceed with restoring the Hook’s seaward shore later this year with 50,000 tons of 3- to 12-inch rounded cobble and gravel.
It will be stockpiled in two areas along the Hook before being transported to “nourishment sites,” according to the environmental impact statement on the project.
While that’s happening, the Corps of Engineers will monitor the impact of dam removal to determine how much restoration is needed, Corps spokeswoman Patricia Graesser said.
Based on analysis of sediment transport by the U.S. Geological Survey, the erosion situation at the Hook will improve only after several years.
“We will continue to do annual surveys and to monitor and find out what the effect [of dam removal] is,” Graesser said in a recent interview.
“We won’t really know until the dams are completely out and after some time is passed.”
The only work done annually on the Hook is routine condition surveying that costs about $20,000 to $30,000, she said.
The last erosion control work was done in 2002. Such work is routinely conducted every five to six years, Graesser said.
The Corps will make decisions about what work needs to be done and when based on “real-time” observations and “based on what we see with an understanding that less material or less frequent work may be needed once the sediment from behind the dams moves out from the river,” she added.
The movement of sediment will be largely dependent on storms, “so rates wouldn’t be constant and reliable,” Graesser said.
Nearby bluffs traditionally also feed the Hook, but that source has decreased over time, she added.
The dams have reduced sediment flow to those bluffs by 55 percent, according to the Corps.
“The Corps’ plan is to continue to survey annually and make decisions, Graesser said.
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Senior Staff Writer Paul Gottlieb can be reached at 360-417-3536 or at paul.gottlieb@peninsuladailynews.com.
