Construction is winding down for the season on the first of 24 wildlife underpasses recommended for the 20-mile stretch of U.S. Highway 160 between Bayfield and Durango.
Last summer, the Colorado Department of Transportation launched the construction project between mile markers 97 and 98 on Highway 160, about five miles east of Colorado Highway 172. It is funded by Highway Safety Improvement Program funds with a 20 percent match from the state. The tunnel is designed to facilitate safer wildlife migrations and effectively battle La Plata County’s grim record for most wildlife-related automobile crashes for the second year running. Crossfire crews are also widening the highway shoulders and installing 8-foot wildlife fencing on both sides to funnel animals through the underpass.
As of Wednesday, the large-mammal crossing is 40 percent complete. At 37 feet wide and 13 feet in height, the tunnel will be a sizeable structure. It’s also a pricey one at about $7 million. If it sounds overbuilt, CDOT Region 5 wildlife biologist Mark Lawler said the crossings are large for a reason.
“A number of factors are considered when determining the appropriate size of structure to serve as a wildlife crossing, such as the desired species to utilize the structure, the required length of the underpass and the amount of vertical relief the terrain topography affords at the structure location,” he said. “The U.S. 160 Dry Creek underpass is intended for mule deer and elk. These animals require large structures that provide openness, as these wary prey species would be hesitant to enter something that resembles a cave or a location that could conceal a predator.”
Bear and smaller species like coyotes and turkeys are also expected to make use of the crossing. Lawler said the “sloping, concave terrain and cover” offered by nearby woodlands will naturally herd wildlife through the tunnel.
The 24 underpass proposals, as well as small-mammal crossings every 1,000 feet, come at the recommendation of an environmental impact assessment, and CDOT spokeswoman Nancy Shanks said CDOT will eventually build all of these structures as money allows, on no specific timeframe.
But not all the recommended structures will necessarily come at the high price of the tunnel under construction, Shanks said. Some of the large-mammal crossings in the region are retrofitted bridges, or double as culverts.
“The cost of an underpass construction will vary, depending upon the overall improvement being made, location and year of construction,” she said.
It’s still a lot of infrastructure for wildlife. Shanks said CDOT does hear from citizens who would like to see more infrastructure for drivers, but she said the wildlife crossings directly benefit humans as well.
“Creating safe passages for wildlife is important for people,” she said. “All the projects have safety mitigations, from wider shoulders to signage and passing lanes. It’s for the safety of motorists as much as connectivity for animals.”
Wildlife-mitigation projects on major highways are ongoing throughout Colorado, other Western states and Canada. One mammal crossing is installed west of Durango toward Cortez. Last spring, work began on a series of wildlife underpasses and overpasses on Colorado Highway 9 between Silverthorne and Kremmling. Vehicle collisions with wildlife on that highway have resulted in several human fatalities.
CDOT consulted a Colorado Parks and Wildlife biologist to identify areas where wildlife is likely to get hit and where animals’ migration routes may intersect with highways.
“We’re very happy to see them, not only to help the animals out, but to avoid collisions,” said Parks and Wildlife spokesman Joe Lewandowski.
“There’s significant mortality with our deer herds, and as populations grow, so does the number that get hit.”
Statistics released by CDOT late last month show that once again, La Plata County is leading the state in wildlife-vehicle collisions, with 306 reported in 2014, up from 252 in 2013. The area between Bayfield and Durango is a proven hot spot for those crashes.
Lewandowski said Highway 160 west of Durango is a major migration corridor from the Weminuche Wilderness to the lower elevation. “I’m sure it’s not cheap, but obviously, anything that can be done to help wildlife is something we’d support. We talk about deer and elk, but other critters get to use them too.”
Fencing and other blockage can interrupt migratory patterns, but the intent of the underpasses is to divert the animals without throwing them off their path.
Lewandowski said Southwest Colorado corridors, including Highway 160, are dividers between the summer and winter ranges.
“The good thing about the corridor is that once (the animals) get south of 160, there’s a lot of tribal land that’s basically open and Forest Service land and BLM land, and there is a good winter range where they can get out of the snow and forage.”
Construction crews will take a winter break and resume work when weather permits. The anticipated completion date of the single underpass is summer 2016.
jpace@durangoherald.com
