Sandbags are ready to be filled on Lower Southfork Road southwest of Cody just in case the Shoshone River backs up into the property and homes of residents along the south fork of the Shoshone.
The rising level of ice at a Park County bridge 12 miles from Cody is stopping the flow of water trickling down from the nearby Absaroka range, and has already caused issues for one homeowner, said Jeff Martin, Park County Homeland Security director.
“As that ice piles up, it creates a dam and the water back flows upstream – and we have some pretty localized flooding to this point,” Martin told Cowboy State Daily. “If residents need sandbags to help alleviate some of their concerns, we’ll take them sandbags.”
But the rising ice also is crowding the bridge and could cause damage.
Park County Engineer Brian Edwards said if the ice continues to rise, the county may have to close the bridge.
“There is a concern, because the ice and the water can provide substantial uplift pressure,” he told Cowboy State Daily. “It’s mainly the joints at the abutments and at the piers. They’re designed to withstand some pressure, but if the ice pressure gets too much on it, it can shift the bridge or bend bridge components or connections, and could render the bridge structurally unstable.”
Sediment Buildup Is To Blame
Edwards explained that the issue stems from rising sediment levels at the mouth of the Shoshone River where it empties into Buffalo Bill Reservoir.
“Where things are changing is between the bridge and the reservoir,” he said. “There’s just more sandbars being built up, and that just slows the water and restricts the flow, and the ice starts from there and it just builds up that backup stream.”
Edwards said long-term mitigation of the problem would involve dredging the sediment built up at the mouth of the Shoshone River, which would be a long, complicated project.
“It would involve environmental issues and concerns there to do that,” he said. “But that would be a lot of coordination with the Corps of Engineers and the Bureau of Reclamation too, for the reservoir.”
Edwards was quick to douse rumors that the bridge itself is to blame for the ice jam backing up the river.
“If you take the bridge out of the way, the ice is still going to build up,” he said. “The bridge doesn’t help the situation, but it’s not the problem.”
Not The First Time
This is the second time in the last few years that the rising ice has caused county officials to be concerned about this particular bridge.
Edwards said the last time in 2019 was severe enough to close the bridge, forcing residents on the other side to drive an additional 5 miles to get to town.
“Last time it closed, I want to say it was for about two weeks,” said Edwards. “And it’s an inconvenience, but the residents that live there are fortunate that they do have another way in and out.”
Edwards said the difference between four years ago and now is that this time the ice build-up is coming much earlier in the season.
“This ice build-up is at about the same level as it was in 2019,” he said, “but it’s about a month earlier from what it was before.”
Edwards said that when the same situation happened in 2019, county officials enlisted the help of both the Wyoming Department of Transportation and the Army Corps of Engineers, which inspects the county’s bridges. He said the county is relying on that same assistance for this situation.
“(We’ll) monitor the bridge and make a decision whether or not we need to close it at some point,” said Edwards. “And then they will inspect it afterwards to see (if there is) damage and see if anything needs to be done.”
Black Sand and Dynamite
There are a few options to help address the situation, Edwards said.
Crews attempted to break the ice with heavy equipment earlier this week, but he said that was just one of several options officials may try to ensure the bridge is safe.
“If we can keep black sand on the ice on either side of the bridge, when it’s sunny during the day, it collects the heat and it just softens the ice a little bit,” he said. “But if it gets really bad, there are things on the Corps side that can be done.
“I mean, it involves explosives, but there’s a lot of things that can be done.”
However, building a taller bridge is not an idea the county is entertaining.
“We’ve got 70 bridges in the county, and this one falls about in the middle of the pack as far as the condition of the bridge — it’s not in bad shape,” Edwards said.
“So, we’re talking in excess of $3 million to replace the bridge, at least, with today’s construction prices – plus there’d have to be a lot of fill on either side to even raise the bridge. So I think we’re a ways out for doing something like that.”
Waiting Game
Until more long-term solutions can be found, county officials are playing “a waiting game,” said Edwards.
And with a coming cold front and more snow set to hit the area, officials are watching the situation carefully.
“I know the temperatures are supposed to get below zero again here in the next week,” said Edwards. “And it was mid-March before that ice receded and fell in last time, so we think we’ve got a ways to go.”
