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2 Of Oregon's Worst Dams For Fish Are Coming Down


Demolition crews knock out first notch in Wimer Dam on Evans Creek, a tributary of the Rogue River.

Demolition crews knock out first notch in Wimer Dam on Evans Creek, a tributary of the Rogue River.

River Design Group

Evans Creek is barely a trickle. A dry summer in Southern Oregon means the important salmon and steelhead creek, a tributary of the Rogue River, disappears below the gravel bed in places. Seemingly stagnant isolated pools are all that remain in some areas.  

Normally, this wouldn’t be considered a good thing. But right now, Brian Barr, dam removal project manager for the GEOS Institute, will take it.  

“Believe it or not, we got lucky from the perspective of not having a lot of water,” he said. “We’re in the middle of the second year of a really bad drought here in Southern Oregon, and it just happens to be the year that we’re constructing.”

WATCH ‘What’s The Deal With Dam Removals’ video:

By “constructing,” he actually means demolishing the Wimer and Fielder dams. These dams were both constructed as irrigation diversions in the early 1900s. By the 1980s, water rights associated with the dams had been abandoned, leaving the two structures sitting defunct and unmaintained on private property.  

Barr said managing water is perhaps the most challenging aspect of any dam removal project.  

“Water is an incredibly powerful force,” he said. “Any time you doubt that you just have to look at the Grand Canyon and see what running water can do when you let it run for a little while.”

Wimer Dam is located in the Rogue River watershed in Southern Oregon.

Wimer Dam is located in the Rogue River watershed in Southern Oregon.

River Design Group

Of course the lack of water is not a complete windfall for construction crews. It’s creating some problems of its own — namely that there’s not enough flow to flush sediment that gets stirred up during construction downstream. Turbidity has been higher than hoped, and workers have been forced to limit in-stream work to about four hours a day to keep levels within permitted range.  

‘Butter Knife’ Demolition  

The Wimer Dam is about 9 miles upstream of where Evans Creek hits the Rogue River. Crews are removing the 11 foot tall, 150 foot wide concrete structure — but not with anything dramatic like explosives. Instead, the chosen demolition method is a giant jackhammer.    

“Most dams don’t go in a puff of smoke with a giant stream of chocolate milk coming out the downstream side,” Barr said, referring to the spectacular use of explosives a few years back at the Condit Dam in Washington.

“Usually you very carefully route water around or through the structure and then you slowly and methodically, like with a dull butter knife, take the concrete down and gently on the side of the bank and into a dump truck,” he said.  

Fielder Dam, a larger structure closer to the Evans Creek confluence with the Rogue, will be removed in a similar way to the Wimer Dam.  

Crews will build a cofferdam, a temporary structure used to route flow out of reservoir water to one side of the dam. Then they can start jackhammering away at the concrete face. Once one side is removed, the coffer will be switched around and the remaining structure will be removed.  

The work is slow, and a bit tedious, but the end result will make a huge difference for fish passage.  

Fish passage limits  

Fielder Dam's fish ladder entrance faces upstream, making it more difficult for salmon and steelhead to find the way.

Fielder Dam's fish ladder entrance faces upstream, making it more difficult for salmon and steelhead to find the way.

River Design Group

Both the Wimer and Fielder dams have fish ladders, to transport fish upstream. But they were added in the 1980s and don’t work particularly well. The steps are too high and the bottom step is several feet out of the water during low flow times.  

In addition, on one of the dams, the entrance to the fish ladder faces upstream. This means fish traveling to spawn have to first ignore all the water coming over the dam face, do a U-turn and head back downstream to enter the fish ladder, and then follow it around as it turns back upstream.  

At optimal flow times, fish can get past both dams, but it’s difficult for them, said Bob Hunter, a board member of WaterWatch of Oregon who has been the leading the legal effort to get Wimer and Fielder dams removed.  

“Any delay and loss of energy for salmon, who don’t eat on the way up, reduces their likelihood of spawning success, even if they get by the obstruction,” he said. 

In fact, when Oregon Department of Fish and Wildlife Biologist Jay Doino went to salvage native fish stranded after the first cofferdam at Wimer was constructed, he didn’t find any.  

“What we found was were all non-native species, we found red-side shiners, bull frog tadpoles, actually only one of those, and a whole lot of ringed crayfish,” he said. “What we didn’t find what we’d hoped to find, juvenile coho and steelhead, possibly cutthroat trout, suckers, skulpins, those kinds of things.” 

Demolition crewmember walks Wimer Dam.

Demolition crewmember walks Wimer Dam.

WaterWatch

Doino said fish surveys above the dams in past years have yielded similar results – in part because the still, warm water that collects in the Wimer and Fielder reservoirs isn’t ideal habitat for cold-water dependent salmon and steelhead.  

When the dams are removed, the reservoirs will become creek again, and better habitat. Doino said those native fish were likely present earlier in the year, when flows were higher. But as waters warmed, they went on the search for better water quality.  

“Then they had no choice to move down stream,” he said. “Hopefully they’ll make it to the Rogue River.  With dame removals, they’ll have a good opportunity to move upstream where water quality is better as well.”

Hunter said removing the Wimer and Fielder dams will open up Evans Creek for steelhead, fall chinook, and federally protected coho salmon.  

“By doing the two projects together, we get the sort of synergistic benefits of removing two of the remaining barriers to access this habitat for fish,” he said. “We’re talking about 70 miles of good salmon and steelhead habitat that now fish will have unimpeded access to.” 

Some Of The Worst  

Because of this significant restoration potential, the state of Oregon has singled the Wimer and Fielder dams out on its Fish Passage Priority List.  The goal of this list, according to ODFW Assistant Fish Passage Coordinator Ken Loffink, is to identify the human-made barriers on Oregon waterways that pose the biggest obstacles for fish.  

“We factor in habitat, whether fish were listed, number of native migratory species, and it spit out a number, and we ranked them accordingly,” he said.  

Threatened coho salmon jump up against the Wimer Dam.

Threatened coho salmon jump up against the Wimer Dam.

ODFW

ODFW lists the Fielder and Wimer as two of the 10 worst barriers to fish passage in the state – significant, considering there are more than 40,000 manmade obstacles on Oregon waterways.   Included in the top 10 along with the relatively small Evans Creek dams are the behemoth Hells Canyon Dam on the Snake River and the Detroit Lake Dam on the North Santiam River.  

“A 5-foot dam could be a full barrier to fish passage just like 100-foot dam.  Now, a 5-foot dam would be much easier to fix… than a larger one,” Loffink said. “But certainly smaller dams can block fish passage just as well as a big one in the right circumstance.”

The priority list is a starting point for planning fish passage projects, but it also has a heftier influence.  

“In statute, if a barrier is listed on the top-10 priority list and ODFW can come up with 60 percent of funding, then the ODFW Commission can mandate that fish passage can be provided,” Loffink said.  

That means the state can force owners of these worst-offending dams to either remove them or provide fish passage. Loffink said this rule hasn’t been used yet, but it can be a useful tool to encourage dam owners to provide for fish.  

Recovery Timeframe  

Back at the Wimer Creek Dam site, demolition crews are basically on schedule – despite having to limit working hours because water quality issues and wildfire rules restricting the use of heavy construction machinery in wooded areas.  

With a little luck in the form of heavy rains this winter, nearly 100 years worth of sediment buildup will washed out of Evans Creek. Salmon and steelhead are expected to begin to show up in higher numbers immediately, but a return to more natural runs likely will take several generations of salmon.  

Demolition crews are required to have both dams removed by mid-September, before fall chinook begin returning to Evans Creek.  

“Nothing is left behind. We will take every piece of concrete that we can find out of the river,” said Barr, the project manager.  

Concrete from Wimer Dam removal is prepared to be hauled away.

Concrete from Wimer Dam removal is prepared to be hauled away.

WaterWatch

Barr has worked on more than 20 dam removal projects over the past couple decades. At about three years in the making  - since Hunter secured agreements with the landowners on either side of the dams - this project has moved at what he calls “breakneck speed.”   Yet, he said, it was all an abstraction until construction actually started.  

“That’s when it starts getting real, when the construction crews shows up and you start putting up the construction fence,” he said. “That’s when the project is really happening, even though it started three, four, seven years earlier with discussions with the landowners and the planning process.” 

But he doesn’t expect to feel the personal and professional satisfaction of a job-well-done for some time.  

“Honestly, where I kind of tear up, or well up, or get really excited is when I go back in about a year,” he said.  

“It’s when I have to go back and take repeat photos and I’ll look at the picture I have.  Okay I was standing on this rock and that tree was in the middle of the frame and there’s a big piece of concrete.  And then I set it down, and I frame up that same image. And it’s a creek.  That’s where I feel it. ”  

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