The Colorado Department of Transportation has installed a huge bridge-like structure that will allow wildlife to safely cross U.S. Highway 160 near Chimney Rock National Monument, 37 miles east of Durango.

An overpass, measuring 100 feet long, 20 feet tall and 72 feet wide, was installed east of the junction with Colorado Highway 151, and a slightly smaller underpass was installed west of the intersection. The wildlife crossings were slated for completion in November 2021. However, a final date has yet to be determined. It is the third such wildlife overpass in Colorado and the first in the southwest corner of the state.

“If we have cooperation with Mother Nature and weather, there’s a good chance that we can get this done this year,” said Lisa Schwantes, spokeswoman for the Colorado Department of Transportation.

The underpass and much of the deer fencing that will run along the highway are complete, but project managers will determine whether to extend the project into the spring in coming weeks.

The overpass needs to be backfilled and wing walls that support the arch need to be placed before vegetation is added.

CDOT and contractor Ralph L. Wadsworth Construction are now working on the road above the underpass. The goal is for that work to be done by the second week of November so the portable light signals that alternate one-lane traffic can be removed and free-flowing traffic can return, Schwantes said.

The overpass and underpass, which are about a half mile apart, are the largest structures in the sprawling infrastructure project, which will include 8-foot-tall exclusion fences, earthen escape ramps and deer guards, a new left-turn acceleration lane at Colorado Highway 151 and 2 miles of pavement resurfacing.

The project started in March after Gov. Jared Polis signed a 2019 executive order aimed at conserving the migration corridors and winter ranges of big game, such as elk.

The project’s price tag of about $11 million covers $7.65 million awarded to Ralph L. Wadsworth Construction and was funded largely by CDOT with significant contributions from the Southern Ute Indian Tribe and Colorado Parks and Wildlife. Schwantes said the project is on budget.

CPW and CDOT identified the 2-mile stretch of road as a critical migratory corridor for elk and mule deer.

“In particular, this migration route is super important to not just Colorado, but New Mexico and the (Southern Ute Indian) Tribe,” said Brian Magee, land-use coordinator with CPW’s Southwest Region. “We think that migration is a learned behavior. And so the animals are telling us where they’ve been shown to cross.”

The elk population in the San Juan Basin continues to rebound after aggressive hunting in the early 2000s left the population at a low of 18,200. The current population estimate of 22,000 elk is still 3,000 fewer than CPW’s goal of 25,000 to 28,000.

In the most recent San Juan Basin Elk Herd Management Plan released by CPW in September 2020, managers expressed concern about habitat and migration corridor loss because of development, natural gas well projects and outdoor recreation.

“Actions to enhance and protect important elk habitat will be essential to increase the elk population,” CPW wildlife biologist Brad Weinmeister wrote in the management plan.

CDOT estimates the new wildlife crossing will decrease wildlife-vehicle crashes by 90%, in line with the decrease CDOT observed after the Colorado Highway 9 Wildlife Crossing Project between Kremmling and Silverthorne, Schwantes said.

Schwantes added that 60% of all collisions along the 2-mile stretch of U.S. Highway 160 are animal-vehicle.

CPW ranks every tenth of a mile section of highway for animal mortalities. Highway 160 from Cortez to Pagosa Springs has one of the highest rates for mortality on the entire Western Slope of Colorado, Magee said.

The hope is that the new corridor will protect both drivers and wildlife.

“All kinds of critters will likely be using this,” Magee said. “They’re not just for elk and deer. They facilitate safe passage for all kinds of critters, big and small.”

Magee was quick to point out that the new overpass and underpass won’t solve all of the problems that elk and other animals face.

“In terms of this specific migration corridor, this is just one of many along the U.S. Highway 160 corridor,” he said. “It’s not going to be the thing that saves or single-handedly improves the elk population issues and the recruitment issues that we’ve been seeing in the San Juan Basin.

“The reality is there are dozens and dozens of these structures needed all across the Southwest, and, frankly, tons of them across the state of Colorado,” he said. “We know where they should go. We know what works. We know what doesn’t work. We just need more funding.”

CDOT and CPW are working together to add migration infrastructure to as many road projects as they can. CDOT will incorporate two wildlife underpasses into the nearly $100 million realignment of U.S. Highway 550 south of Durango, Schwantes said.

There are also plans for a new underpass along Highway 550 north of Ridgway Reservoir. Contractors will bid on the project this winter and start next spring or summer.

“A wildlife overpass can cost as much as $2 million,” Schwantes said. “But when you’re looking at a project that is tens of millions of dollars, then it’s quite a minimal cost to add that type of a feature in for the benefit that it has for the motorists’ safety and the wildlife’s safety.”

ahannon@durangoherald.com