Seasonal flooding is threatening the county’s pathway bridge across the Gros Ventre River north of town.
The runoff could also threaten the highway bridge if erosion continues, Pathways Coordinator Brian Schilling said.
“That would potentially be at risk should the river really decide to change the course and continue to erode those abutments,” Schilling said.
The pathway has closed every spring since 2017 due to flooding. In 2018 the county made short-term emergency repairs by installing riprap on the riverbank.
County commissioners voted Tuesday to approve a contract for $443,832 for further riverbank work, including stabilizing the banks several hundred feet upstream.
That’s despite concerns about river impacts voiced by several advocacy groups. Snake River Fund Executive Director Jared Baecker worried the bank stabilization could harm cottonwoods along the river, which depend on spring flooding to regenerate.
“We would encourage as little rip rap as possible,” Baecker said. “There’s many other techniques, recognizing there’s no gigantic piggybank to fund all this stuff.”
Tom Segerstrom, director of Teton Conservation District, warned against interfering with the river upstream of the pathway.
“My advice is to stay out of the river itself and protect the infrastructure that is important to protect,” Segerstrom said. “We are fully in favor of protecting this infrastructure and just finding a way to let the river do what it needs to do. It’s just a matter of, history has shown that when we levee or stabilize something with unstable substrates like the Gros Ventre, it tends to do the end run on you and winds up costing you a lot more in the future.”
Public Works Director Heather Overholser said there will be opportunities to explore other techniques to protect the bridge.
“The river is dynamic. It will continue to change as years go by,” Overholser said. “We’re going to be looking at future restoration, armoring and potentially pathway raising.
“Some of these other opportunities that are being discussed today could definitely be implemented in the future.”
The commission approved the bank stabilization contract with CM Owen Construction in a 4-1 vote. Commissioner Luther Propst was opposed, worrying that “we’re starting a war with the river that’s just going to move us further and further up.”
“We’re making a very long-term decision here, possibly permanent, extending our battle with river management further upstream,” Propst said. “I’m uneasy with that.”