Rain triggering rock, mudslides forces I-70 shutdowns in Colorado as new safety norm | SummitDaily.com

Rain triggering rock, mudslides forces I-70 shutdowns in Colorado as new safety norm

Bruce Finley
Denver Post
CDOT contractors work to re-stabilize Glenwood Canyon in western Colorado above the Colorado River and Interstate 70 on August 18, 2022. Even routine rainfall over a 51-square-mile burn scar area now can set off slides and state officials regularly shut down this highway as a precaution against catapulting boulders and mud.
Andrew Knapp/Courtesy photo

Twice this past week, big orange trucks commandeered Glenwood Canyon in western Colorado during rain, shutting down Interstate 70, one of the West’s key routes, a highway long celebrated as a national engineering wonder.

These disruptions resulted from a recent decision by state and federal authorities to extend a policy of closing I-70 in the canyon whenever the National Weather Service issues flash flood warnings. Precautionary closures must continue, authorities say, until geologists determine rock and mud is less likely to catapult downward.

All canyons naturally produce slumps and slides. But in 2020 the Grizzly Creek Fire scorched 51 square miles around Glenwood Canyon and burned away trees and shrubs that once stabilized super-steep cliffs, leaving chutes and gullies like loaded guns above the millions of cars and trucks rolling below by the Colorado River.

Now even relatively light rain — a quarter-inch over 15 minutes — can create havoc, federal geologists and meteorologists warn. CDOT records show agency crews have closed I-70 from Glenwood Springs to Dotsero 25 times since the fire, prohibiting travel for one to 12 hours each time.

The economic cost to the nation of an I-70 closure is estimated at $1 million an hour.

This emerging new norm for managing hazards on an essential highway through Glenwood Canyon reflects difficult decision-making that prioritized public safety. Deliberations like this are expected to widen as cascading impacts of climate warming include increased avalanches in addition to flooding and landslides. Beyond Glenwood Canyon, more land around the West is becoming more unstable as fires burn bigger and hotter — especially in Colorado where wildfires intensifying over several decades amid rising temperatures, drought and bug infestations have left 34 scars covering more than 700 square miles.

Read more at DenverPost.com.

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