Willwood Silt Dilemma

After a large silt release turned the Shoshone River gray below the Willwood Dam and prompted a public outcry in 2016, federal, state and local officials formed a trio of working groups to study the problem.

The announcement might have inspired hope that a combination of technology and attention would eventually solve the decades-old issue of silt behind the dam.

But recent watershed studies indicate it may be impossible to stop much of the sediment from reaching the river; even those who feel there’s some hope to slow the influx of silt agree it will be a long-term, uphill battle to stop a fraction of the problem.

Turbidity downstream of the Willwood Dam has been tightly regulated since the Clean Water Act was enacted in 1972. In the more than 45 years since, silt has been halted at the dam, piling up with nowhere to go. So when the more than century-old structure needed repairs in the fall of 2016, silt escaped downriver.

Many believed the gray sludge would result in a massive fish kill. However, Wyoming Game and Fish Department fisheries biologists later determined the damage was minor in comparison to initial fears.

Still, three working groups were deployed to attack the problem.

Working group three is charged with studying where the sediment is coming from and addressing it.

The group is made up of representatives from every major stakeholder, from federal and state entities to Park and Big Horn County representatives.

At the center are two local volunteers: Roger Smith and Ann Trosper, an odd couple by some measures.

Smith’s hands are stained from hard labor, his clothes tested at every seam. He isn’t thrilled with being in front of the camera, but he’s the chairman of the board of the Willwood Irrigation District and finds defending the district a necessary task. Smith has also been managing operations while the district looks to train a new manager.

Trosper is a jack of all trades. She helps wherever needed, from taking minutes at the Park County Predator Board to managing the area’s conservation district. Trosper is more at home with paperwork — a large part of her job at the Powell/Clarks Fork Conservation District — but is willing to get muddy. She’s been involved in area watersheds for more than a decade.

Trosper is all business, a get-to-the-point kind of person. Smith is all heart, kind to his cows and willing to help a neighbor in a crisis at the drop of a hat. But they see eye to eye on many of the issues.

Both agree Powell would not thrive without water or the agricultural community created by the irrigation district. Both agree a healthy river is the top priority. And while they’d love to have an answer to the issues at hand, both are adamant that the main culprit is the porous nature of the soil in the Shoshone River Valley.

“The sediment that’s coming in naturally is just that, and there’s not a lot you can do about it,” Trosper said. “The past operational constraints put on [the turbidity of the river below the dam] didn’t recognize any of that.”

Smith agrees, having watched data stream into his office hourly from new technology funded and installed by the Wyoming Department of Environmental Quality and the U.S. Geological Survey. The river is being monitored both above and below the dam.

“The information coming in is so important to the process. We need more of it,” Smith said, adding, “But my gut feeling is the stuff that’s coming from the [agriculture] community is minuscule compared to what’s coming in naturally.”

One recent investigation of the Buck Creek watershed was an eye-opener for the work group.

“Buck Creek samples were way worse than anything that happened at the dam and it happens naturally,” Smith said. “People don’t see the sediment coming in above the dam, just downstream.”

“[The creek] was rolling nothing but mud; you could’ve walked across it without getting your feet wet,” Trosper quipped.

There are 15 watersheds between the Buffalo Bill Reservoir and the Willwood Dam, each contributing to suspended sediment in the river.

Dredging behind the dam is still an option, but it’s extremely expensive, Smith said. The process could cost between $6-$10 million and “the implication has been that our small community should bear the brunt [of the costs],” he said. Even if they do dredge, the sediment will return long before the bill for dredging has been paid.

Laura Burckhardt, Wyoming Game and Fish Department aquatic habitat biologist, also holds a volunteer seat on work group three. The Game and Fish and the irrigation district have been adversaries at times, yet, for the most part, Burckhardt agrees with Smith and Trosper.

Burckhardt said farms upstream of the dam are smaller and less of a contributor to sediment levels in the Shoshone River. She concurs that much of the erosion is natural, but feels more can be done. Burckhardt sees potential improvements to creek bank erosion, runoff from farming and overgrazing and road erosion and washouts — especially in the McCullough Peaks. She’d like to see more pivot irrigation, bank stabilization and overflow ponds.

“There’s a variety of sources we can do something about,” Burckhardt said. “It’s a very complicated situation. There have been working groups dealing with the issue since the ’50s and it’s not going to be a fast fix.”

Burckhardt considers bank erosion to be an unnatural source of sediment and points to possible fixes — such as manmade beaver dams or shoring up the banks with vegetation or manufactured products. She knows stream restoration projects are hard work, but says it’s worth the effort.

All efforts rely on funding, meaning education may be the cheapest way to slow sediment and runoff.

“You have to find a balance of how much money you’re willing to devote to projects,” Burckhardt said. “Hopefully getting the word out will help get more people to reduce accelerated sediment erosion.”

With each meeting and conversation, perceptions slowly change.

“I’m coming to realize the majority of the people we hear from have an open mind. Most, 90 percent, are that way,” Smith said. “But there are still very vocal [opponents]. The best thing that can happen is everybody sitting down and looking at the facts.”

Working group three sponsored a fact-finding tour last summer.

“When they were able to see the problem for themselves you could tell they were having an ‘aha’ moment,” Trosper said. “You can’t believe the ‘aha’ moments we had with the people writing the regulations when we’re standing out there.”

The group is looking at every opportunity to stabilize erosion-prone banks and minimize runoff where they can. They are determined to make progress.

“Even if all we can do is improve runoff by 10 percent, it’s important that we do it,” Trosper said.

The effort still faces many critics, ranging from recreational users to some in the agricultural community. Recently, Trosper received a letter accusing her of picking on ag producers in the efforts to control runoff.

The criticism stings. But there is hope that keeping an open dialogue will resolve many misconceptions.

“We’re not aiming at [agricultural runoff]. We’re not aiming at anything,” Trosper said. “All we’re trying to do is understand.”

Source: Powell Tribune