Road access in Denali National Park and Preserve is being restricted due to a long-running landslide issue that has been exacerbated by climate change, the park announced Tuesday.
The lone road through the park spans 92 miles. Nearly half it — the area west of mile 43 — closed Tuesday to nonessential vehicles, pedestrians and bikes because of unsafe conditions caused by a landslide in the Polychrome Pass area, according to a statement from the park.
Buses, the main way for visitors to access the park, will continue to run to mile 42. There were more than 80 backpackers west of Polychrome Pass that would need to be relocated, a park spokesman said.
According to the park, slides have affected the area since at least the 1960s but used to require maintenance every two to three years. In recent years, the road has seen slumping of a 1/2 inch per day, up to 3 inches per day, by August 2020.
Rains earlier this month appear to have caused the rate to increase significantly, with much of the landslide moving downhill at over 10 inches per day, the park said.
Park spokesman Paul Ollig said the dramatic increase in the rate of movement observed over the past week meant that the slumping had finally exceeded the park’s ability to maintain the road in a way that was safe for vehicle traffic, particularly buses and heavy equipment.
“Additionally, the roadbed through the slide has become very soft, and a rolling, pumping of material on the outside of the driving surface has been observed,” Ollig wrote in an email. “We expect this rate of slumping to continue, and possibly even continue to increase over the coming days and weeks.”
Climate change “has taken what was previously a problem solved by maintenance staff performing road repairs and made a challenge too difficult to overcome with short-term solutions,” the park statement said.
Don Striker, the park superintendent, said the National Park Service is working with the Federal Highway Administration and other agencies on a long-term solution to maintain road access through the area.
The statement says front-country trails and backcountry access remain open, as does the Kantishna airstrip, which is near the end of the road. The visitor center, near the park entrance, will continue providing daily ranger services, the statement said.
Campers at the Wonder Lake Campground, near the end of the road, and in backcountry areas west of Polychrome Pass will be relocated to areas east of the closure in the coming days, according to the statement.
All campers at Wonder Lake had been notified Tuesday, but some others in the backcountry might still be unaware of the road closure and relocation effort, said Ollig, the park spokesman. There were a total of 84 campers and backcountry users west of the closed pass as of Tuesday, he said.
The Wonder Lake Campground and Eielson Visitor Center, at mile 66, were closing Tuesday for the rest of the year.
The park road typically closes to vehicle traffic beyond mile 30 in mid-September.
Several days in September traditionally are set aside for winners of a special lottery to drive as much of the road as weather conditions allow. Paul Ollig, with the park, said he did not have an update Tuesday on this year’s lottery.
More than 601,100 people visited Denali National Park in 2019.
Alaska Public Media’s Casey Grove contributed to this report.