CATHLAMET — Building a dike through the heart of a wildlife refuge may not seem like an ecologically sound thing to do. But a $6 million U.S. Army Corps of Engineering project just west of here makes that claim.
Under a corps contract, a Chico, Calif., company is building a mile-long “setback” dike through part of the Julia Butler Hansen Refuge for Columbian white-tailed Deer.
The project’s primary purpose is flood control. The new, mile-long dike will replace a portion of the Steamboat Slough levee that the Columbia River is undermining and which engineers say can’t be fixed. If the dike fails, floodwaters and high tides could inundate the deer refuge and possible threaten State Route 4.
But the project is intended to have an ecological benefit, and is being funded with corps salmon restoration funds. Once the new dike is finished next year, workers will breach the failing levee, allowing the Columbia to flood about 68 acres of bottomland sandwiched between the old dike and the new.
“This is a unique project for sure, working in the middle of a wildlife refuge.” said Scott Vandergrift, project manager for contractor J.E. McAmis, said during a tour of the work Wednesday.
Before farmers diked them off decades ago, the bottomlands along the Columbia and Elochoman rivers were a hodgepodge of pools, sloughs and timbered marshland created by floods and high tides. Such places are prime rearing habitat for salmon and other wildlife, but development over the past two centuries eliminated a majority of such places from the lower Columbia River.
The failing levee created an opportunity to restore some of them.
Work on the new levee started just before Labor Day after Wahkiakum County, corps and federal wildlife officials finally got clearance from a lone diking commissioner, who had delayed the project over access and other issues.
About 50 workers are on the job, about half of them hired out of the local area, Vandergrift said.
The work is simple. The new dike is being built of sand barged in from nearby Skamokawa Vista Park and an impervious layer of silt trucked in from a quarry in Naselle. About 92,000 cubic yards of fill — enough to cover a football field 50 feet deep — must be hauled into place.
This is handled by off-road dump trucks, rolling on wheels taller than Wilt Chamberlain and hauling more than 30 tons of dirt in a single load. Bulldozers spread the dirt and a roller compacts it. The completed dike will be capped with a gravel road, seeded with grass and will be about six inches higher than the existing dike, said Phil Ohnstad, project manager for the corps.
Ohnstad added that work will shut down for the winter later this week because rainy weather will make it difficult to compact the soil properly.
So far the white-tailed deer, an endangered species, don’t seem much affected by the work. In fact, their hoofprints dapple the work site. About half of the herd was moved off the refuge as a hedge against flooding before the work even began, and biologists also scoured the work area for any salmonids that might be lurking in the drainage sloughs in the work area.
“It’s a challenging job for sure,” Vandergrift said.