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Gov. Jared Polis on Aug. 2, 2021, said he was preparing a request for federal disaster declaration due to extreme damage to Interstate 70 through Glenwood Canyon from the mudslides. (Colorado Department of Transportation)

Gov. Jared Polis said he will issue a state disaster declaration and seek federal help to respond to mudslides that have caused “extreme damage” to Interstate 70 through Glenwood Canyon and closed part of the major east-west thoroughfare since last week. 

It could take a few days or a few weeks to clear at least one lane of traffic each way on the highway, a major transportation artery, Polis said. 

His announcement comes as swaths of Western Colorado on Monday are being watched for flash flooding due to heavy rainfall, including the Grizzly Creek fire burn scar above I-70 in Glenwood Canyon, according to a weather service advisory. 

The full extent of the damage is unknown as mud-clearing efforts have been suspended due to storms and parts of the highway remain covered by 10 feet or more of debris. There is significant structural damage to the I-70 viaduct and to the highway in two areas where mud and rocks, sometimes falling from thousands of feet above, have crashed and damaged an upper deck, while parts of the lower deck are submerged in the Colorado River, officials said. River water is pushing against a retaining wall that keeps the road steady and another that holds up Union Pacific tracks that carry freight and passenger trains. 

“We’re not out of the woods yet with regards to additional damage,” Polis said. 

I-70 through Glenwood Canyon has been closed repeatedly this summer as heavy rains sent rocks and mud tumbling down into the river, blocking and damaging the roadway. Burn scars combined with unusually heavy monsoon rains have contributed to the extensive damage and the closures, Polis said. The region has seen 4 inches of rainfall in five days instead of the usual 2.4 inches in a month. 

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Fire changes the composition of soil along burn areas, making water run off of it — like rain sliding off a car — instead of being absorbed, Assistant State Climatologist Becky Bolinger previously told The Colorado Sun. Flash flooding along burn scars could continue through the monsoon season, which typically runs through September, she said.

Fire mitigation efforts can prevent the burns in the long term, but there will be little opportunity to prevent a similar slide, for example by replanting vegetation, in the near-term, Polis said in a news conference Monday afternoon. Polis was supposed to survey the damage by helicopter, but rain and hail in the forecast kept him on the Front Range.  

Mudslides in Glenwood Canyon shut down Interstate 70 on July 29, 2021, stranding more than 100 people, some of whom spent the night in a tunnel. (Colorado Department of Transportation)

The interstate, used by tens of thousands of motorists each day, is important to recreational travelers and is a major freight highway. The closures have sent increased business to towns along the detour routes, but also have slowed the flow of tourists to Glenwood Springs and other areas that have struggled under a year and a half of pandemic restrictions.  Polis called the closure a setback and said it is important that the highway be fixed before the ski season starts.

Vehicles travel July 31, 2021, along U.S. 40 through downtown Steamboat Springs as part of an I-70 detour. The detour is expected to continue into the week after debris caused significant damage to I-70 through Glenwood Canyon. (Matt Stensland, Special to The Colorado Sun)

State officials have directed trucks hauling freight to take Interstate 80 through Wyoming, and suggested alternate routes for motorists that can add hours to their trip. 

The Colorado State Patrol has shifted resources to the alternate routes that could see increased traffic due to the closure of I-70. The troopers are particularly concerned about heavier traffic on U.S. 40 to the north and U.S. 50 to the south, and are working to keep vehicles that are too long or too wide from attempting to take the narrow, winding Colorado 82 over Independence Pass between Leadville and Aspen.

The Department of Public Safety, along with other agencies, is doing a “means and damage assessment to understand what can happen with the Colorado River to make it less of a problem inside the canyon,” said Stan Hilkey, the department’s executive director. Debris in the river has caused the river to divert into areas it didn’t previously flow, pushing up against the highway in some areas and causing more damage, he said.  

CDOT Executive Director Shoshana Lew, was reluctant to attach a dollar amount to the damage but estimated it could be in the tens of millions of dollars. 

Last week, more than 100 people had to spend the night on I-70 through the canyon after a storm set off mudslides in the fire-burned area. Nearly 30 of those trapped took shelter in a tunnel until crews could carve a path through the mud to reach them, in the most dramatic weather-related incident in the canyon in years.

Shannon Najmabadi

Shannon Najmabadi covered rural affairs and the rural economy for The Colorado Sun from 2021-2023. Email: Twitter: @ShannonNajma