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Crews begin removing Dillon Dam on the Umatilla River

It took 20 years of planning, studies and grant writing, but removal of the Dillon Diversion Dam is finally underway on the Umatilla River.

A pair of excavators rumbled over the dry, rocky riverbed Wednesday morning two miles downstream of Echo, while project managers watched from a clearing along the stream bank. One of the backhoes, fitted with a massive air chisel, moved into position and sliced into the aging concrete like a hot knife through butter.

“I’ve been on a lot of construction projects, but never a deconstruction,” said Michael Ward, executive director of the Umatilla Basin Watershed Council.

Ward, who was hired by the watershed council last November, is the third director to help carry the project across the finish line. His predecessors, Greg Silbernagel and Jon Staldine, also played key roles in applying for funds and rallying local partners.

Work officially began July 13 to tear out the dam, which had been identified as a fish-blocking, water-clogging burden. Not only did the structure pose a barrier to salmon, steelhead and lamprey, but due to its location gravel bars would routinely wash over the irrigation headgate during high flows, leaving ranchers to clean up the mess.

Crews will have until Sept. 15 to finish the job, which is around the same time fall chinook usually start making their way back up the river to spawn.

Fish passage is, of course a major theme of the project, Ward said. But that’s not the only perk to removing the dam.

“There’s water savings. There’s ecological benefits. There’s economic benefits for the local irrigation districts,” Ward said. “This has all hallmarks of a great project.”

Mutual interest

Dillon Dam was originally built in 1915 and now serves five landowners as part of the Dillon Irrigation Company, with water rights dating back to the 1890s.

Mike Taylor, who owns the Double M Ranch in Echo and Stanfield, acts as president of the small irrigation company. He uses Dillon water to irrigate 1,650 acres of his own property, where he and his family raise about 1,300 cows.

It was Taylor’s idea, albeit jokingly at first, to remove the dam, which was proving to be a headache to maintain. Every year — sometimes twice a year — he said landowners were forced to bring in their own equipment to clear out gravel that washed downstream, plugging up their headgate and blocking access to the dam’s juvenile fish ladder.

Taylor discussed the issue with Bill Duke, district fish biologist for the Oregon Department of Fish & Wildlife, and Brian Zimmerman, fish passage supervisor for the Confederated Tribes of the Umatilla Indian Reservation. As it turns out, there was mutual interest toward losing the dam.

Over the course of multiple fish tagging surveys, Dillon Dam was pegged as a top offender for delaying native salmon and steelhead in the Umatilla River. Though the dam was rebuilt in 1976 with fish ladders on either side of the 200-foot structure, Duke said they are not always adequate for passage needs.

“Fall chinook and coho, they tend to come up to that obstruction and get delayed there. They end up spawning there below the dam,” Duke said. “It’s not conducive for rearing juvenile salmon and steelhead down there.”

During low summer flows, the ladders are too steep for juveniles to swim freely upriver as they try to seek refuge in cooler water. Pacific lamprey were also stonewalled at the dam after they were reintroduced by the tribes into the Umatilla River.

“We’re trying to get passage for all native fish,” Duke said.

Point of diversion

Sides agreed they wanted to see Dillon Dam removed. The question was how, and where, irrigators would receive their historic Dillon water rights.

The idea remained on the shelf until 2011, when the local watershed council got involved. Silbernagel, who now serves as the district watermaster for the Oregon Water Resources Department in Pendleton, was instrumental in developing a project feasibility study that was published in 2014, with funding from the Oregon Watershed Enhancement Board.

The study recommended the Dillon point of diversion be shifted upstream to the existing Westland Diversion Dam. From there, a two-mile pipeline would run along Andrews Road, bypassing the dam back into the Dillon Irrigation Ditch.

Despite some initial concern about moving the irrigation diversion upstream, the pieces soon fell into place. Silbernagel was able to secure another grant from OWEB for $297,383 toward pipeline construction.

Staldine, who succeeded Silbernagel as watershed council director, brought in another $174,400 from the ODFW Restoration and Enhancement Board last year. The rest of the pipeline funding was provided by Taylor, Dillon and Westland irrigators to the tune of $140,000.

Construction of the pipeline was done in February and March. In addition to bypassing the dam, Taylor said the line will help to improve water efficiency and will save on system maintenance costs.

Taylor said it will be hard to imagine the river without Dillon Dam, a mainstay of his operation for decades.

“It’s been there as long as I’ve been here,” he said. “In the long run, it’s going to be beneficial.”

Dam removal

With the water diversion issue settled, all that’s left is to demolish the old dam.

ODFW crews from John Day have been brought in to do the work, which started last week with several days of fish salvage and water pumping from the river. The dam itself measures approximately 200 feet long, 6 feet wide and 16 feet deep.

Bonneville Power Administration is paying $600,000 for deconstruction, using money from the 2008 Columbia Basin Fish Accords with local tribes, including the CTUIR.

Rick Christian, Umatilla Basin habitat project leader for the CTUIR, began working on the project about two years ago. He said passage obstructions on the lower river need to be dealt with to make sure salmon and steelhead aren’t expending all their energy before they can reach prime spawning ground — what he described as “pre-spawn mortality.”

“Our fish come a long way to spawn,” Christian said. “Let’s make it as easy as possible for them.”

Taylor McCroskey, fish habitat biologist for ODFW, said the agency has identified other obstructions that they would like to remove from the main stem of the Umatilla River to further improve passage, but he remained tight-lipped on specifics.

“We want to get them up into the tributaries so they can spawn in those cooler headwaters,” McCroskey said. “We’re all hoping that we have a lot less fish passage delay here, and a lot more fish moving upstream faster.”


Contact George Plaven at gplaven@eastoregonian.com or 541-966-0825.

Source: http://www.eastoregonian.com/eo/local-news/20170721/crews-begin-removing-dillon-dam-on-the-umatilla-river


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