An excavator moves a boulder while working on a riverbed restoration project at the former site of the Zell diversion dam on the Walla Walla River east of Milton-Freewater.
East Oregonian photo by E.J. Harris
PENDLETON, Ore. (AP) — A diversion dam blocking nearly 50 miles of prime fish spawning habitat on the Walla Walla River is slated for removal by September as part of a decades-long effort to rid the waterways of so-called gravel push-up dams.
Excavators have lifted heavy basalt boulders into the river at Zell Ditch, raising the stream bed to continue redirecting water for farms and pastures. The structure's design mimics natural rapids and allows for passage of native salmon and steelhead, the East Oregonian reported.
Without diversion dams, fish can move more easily into tributaries upstream where they naturally lay their eggs.
“We let those irrigators know we would help them find a fish-friendly way to get their water rights out of the river,” said Brian Wolcott, executive director of the Walla Walla Basin Watershed Council. “If fish can't get to where they naturally spawn, we won't be able to get our populations de-listed.”
Zell Ditch serves 30 separate water rights claims, the oldest dating to 1873. Gravel push-up dams were used to steer water out of the river and support agricultural production along Walla Walla River Road.
Blockage during low flows meant stranding fish, and in the case of chinook salmon, wiping them completely out of the basin. The Chinook were later saved by restoration work by the Confederated Tribes of the Umatilla Indian Reservation.
Now, the basin averages 500 returns upstream of Milton-Freewater per year. Between 500 and 1,000 adult steelhead return to headwaters each year, along with 8,000 to 12,000 bull trout.
“These projects are for environmental benefit, fisheries restoration and water quality,” he said.
The watershed council has invested $13 million in projects since it formed in 1994, Wolcott said, including $300,000 for removing the Zell Diversion Dam.
Funding comes from a number of state and federal sources, including the Oregon Department of Fish & Wildlife, Oregon Watershed Enhancement Board, U.S. Fish and Wildlife Service and Environmental Protection Agency. Wolcott began writing grants 10 years ago to pay for the design and construction.
Richard Langley, who owns 13 acres two miles east of Milton-Freewater, said he has used water from Zell Ditch for 18 years. Water translates to dollars, he said, and he is pleased the project will not only increase efficiency but benefit native fish.
“It fits in with all the other projects up and down the Walla Walla River to increase efficiency and usage,” Langley said. “This is going to be the start of something that's pretty nice for all of us.”