DENVER—As ominous storm clouds gathered in western Colorado over a large area blackened by a recent wildfire, torrential rain fell, and the charred land stripped of vegetation gave way, sending a rush of mud and boulders tumbling down steep canyon walls and onto a major highway.
The July 29 mudslides stranded more than 100 people in their vehicles overnight and caused extensive damage that closed Interstate 70, capping several weeks of perilous conditions in a scenic canyon carved through the mountains by the Colorado River.
