Raising bridges and adding fences allows big game to avoid busy blacktop 

Like so much early, modern development across America, the railroads and highways through Idaho’s Lemhi Valley were not constructed with fish and wildlife in mind. 

First, railroad tracks were laid between Salmon and Gilmore, straight lines of progress carting people to the center of the state to find and deliver a menagerie of precious metals to help build the growing nation. To accommodate the rigid tracks, the river was straightened; leaving the fish without suitable places to rest and spawn. The highway, now known as State Highway 28, followed, and no concessions were made for the area’s deer, elk, moose, pronghorn, and fish, which included ocean-going species such as salmon and steelhead.  

For decades, these developments brought a litany of unexpected consequences. Many big game animals have been killed on the highway, and the precipitous decline in anadromous fish stocks can be traced, in part, to the loss of quality spawning and rearing habitat in the channelized Lemhi River attributing to, in part, a decrease of quality hunting and fishing opportunities. 

Fortunately, a plucky team of state officials, federal land-managers, private citizens, and nonprofit leaders, including the Theodore Roosevelt Conservation Partnership, have banded together to improve the safety of wildlife and motorists on the altered landscape near Leadore, Idaho. 

“It is the coolest project I have worked on in my career,” said Jessie Shallow, a Mule Deer Foundation – Idaho Department of Fish and Game partner biologist, who has worked on the wildlife crossing project for roughly four years. 

The process began when the Idaho Department of Transportation decided to update several of the bridges that cross the Lemhi River to meet federal flood standards. Although not a specific goal of the bridge project, IDFG worked with ITD to incorporate design elements that would hopefully improve wildlife movement under the roadway. Resulting accommodations for wildlife were wider and taller bridges, making the tunnels large enough for wildlife such as deer, elk, and moose to cross under the highway.  

When the bridge replacement project came in under budget, the excess funds were allocated to build wildlife fences that would funnel the wildlife to the new structures. In 2020, the IDT built three miles of funnel fence on each side of the highway, ushering animals to cross the highway under the bridges and not on the asphalt. The fences were a game changer. Fish and Game documented roughly 40 animal crossings in the underpasses before the fence was built, and over 400 through the underpasses per year once the wildlife funnel fence was in place. 

“It is the coolest project I have worked on in my career.”

Jessie Shallow, Mule Deer Foundation – Idaho Department of Fish and Game partner biologist

Project partners are now using more grant funding to extend an existing funnel fence two more miles along both sides of the highway. The location of the extension was prioritized based on frequent road-kill counts, and sadly, a wildlife-vehicle collision which caused a human fatality in that section.  

Shallow predicts that the extended fence will reduce wildlife vehicle collisions by more than 80 percent in that section.  

Using game cameras, Fish and Game officials have captured dozens of animals traveling under the highway. Everything from deer, moose, and mountain lions and even a mountain goat, which was miles from the nearest mountain ranges.  

“It has been a complete success,” said Shallow. 

The only remaining issue on this stretch of Highway 28 was aiding the animals that became stuck inside the funnel fence and needed to exit the roadway. Traditionally, biologists designed steep jump-outs for animals, but in this instance, there was not sufficient space within the right-of-way for those to be constructed. 

Shallow overcame this challenge by adapting a gate project designed in Utah that allowed elk to escape apple orchards. Instead of using traditional V-gates, which allow anglers to access the river, Fish and Game and the Mule Deer Foundation created one-way gates that wildlife could push through to escape the highway side to safety. Think of a beaded curtain in a palm-reader’s hazy shop, but instead of beads, the curtain is made of metal posts that swing only out. Placed on a fence corner, these new one-way gates are wide enough for whitetails and similar-sized animals to leave the road but narrow enough to keep cattle off the highway. 

The one-way gates were immediately successful as Fish and Game tracked a substantial increase in the number of animals that were able to escape the roadway after gaining access at the fence end. Although not the perfect solution, the effectiveness of the one-way gates has been encouraging.  The key to success for these one-way gates is that they must be placed where the funnel fence makes a corner – these are natural areas that wildlife will congregate and attempt to escape. 

While there are many other places throughout Idaho that still need infrastructure to help animals cross roadways safety during their daily and seasonal movements, the bridge underpasses and miles of fencing on Highway 28 are tangible work that directly improve motorist safety and increase hunting opportunity.  

“We are making a difference,” Shallow said. “It is very rewarding.” 

Bryan Young, traffic/operations engineer for ITD agreed and looks forward to partnering with the agency and organizations in the future.  

“It has been very exciting to be part of this project and to build a partnership with the Idaho Department of Fish and Game that will last for a lifetime,” said Young. 

Learn more about wildlife crossing work in Idaho HERE.

Photo courtesy of IDFG

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