Crew moves creek so salmon can survive

Section of Duck Creek rerouted to make room for bike path and free passage of salmon smolt

Posted: Thursday, July 05, 2001

A dried-up section of Duck Creek is getting a new bed and a new life.

The state Department of Transportation is moving the 500-foot stretch of Duck Creek that ran alongside Mendenhall Loop Road at the southwest corner of its intersection with Egan Drive to make room for bike lanes. The new Duck Creek will wander 30 to 100 feet from the road, bordered by fast-growing willows, sedges and grass.

"Before, it was right next to the road like a ditch and it basically functioned a lot like a ditch with fish in it," said Sue Walker, who contracted the stream redesign for the U.S. Fish and Wildlife Service. "This will be able to function a lot more like a salmon stream, which Duck Creek is."

The project is a collaboration of DOT, the Fish and Wildlife Service, the U.S. Forest Service and the National Marine Fisheries Service.

Duck Creek was moved before, so long ago the agencies involved can't remember when.

"It used to be on the opposite side of the road, from the best we can tell," said K Koski, fishery research biologist and habitat coordinator for the Fisheries Service.

That first move turned the creek into a ditch about 15 feet from the road. The soil there was so porous the creek lost 3 cubic feet of water per second, leaving it dry from May or June until the fall rains.

The localized drought created a bottleneck for the 2,000 to 4,000 coho smolt born in the creek each year.

"It's so dry that for seven of the last eight years all of the coho smolt that are in that system had to be moved by buckets," Walker said. "They can't swim all the way to the river."

This time the contractor, Secon, is lining the new creek bed with geotextile, a rubberized material similar to the floor mat in a car. The liner should keep water flowing downstream, rather than soaking into the ground. On top of the liner they're layering 2 feet of gravel, then reinforcing the sides with cobbles to prevent erosion.

The creek bed will shift only 15 feet in some places, but a small hump is being added to protect it from road runoff. Grass planted along the old channel will act as a natural filter for road sand, gravel and oily runoff.

"We want a vegetative buffer between the road and the creek so that road maintenance activities don't contribute to pollution in the creek," said Kris Benson, DOT environmental coordinator. "The buffer will provide a space for plowed snow storage and a filter for runoff and sand applied in the winter."

This year the stream bed will be lined only to the Del Rae crossing, where the water probably will disappear into the ground, Koski said. Next year the U.S. Army Corps of Engineers plans to finish the job, so the creek flows all the way to the Mendenhall Wetlands and the smolts can swim free.

To make room for the new creek bed, DOT had to cut down large spruce and cottonwood trees in its path. That exposed a hill of recycled asphalt.

"It kind of looks like a bomb was exploded," Koski said.

The pile probably will remain visible until willow trees planted alongside the new creek bed have time to grow. Next year DOT also will build a berm to protect the creek from the asphalt, Walker said.

Neighbors will be able to walk along this section of the creek when it is done, Walker said. Though DOT isn't putting in a path, the rocks along the edge of the creek will make it easier to access.

Kristan Hutchison can be reached at

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