High-Impact Weather and Climate Events

The longest (2.8 miles) and largest mass-movement earth failure in Colorado history occurred 3 hours after a short, intense rainstorm, and two weeks after a late spring snowstorm. The fast-moving landslide dropped 2100 feet in elevation and covered almost a square mile of the West Salt Creek valley with 38 million cubic yards of debris. Three local men, who were investigating an earlier, much smaller, landslide, died during the catastrophic event. The toe of the landslide came within 200 feet of active gas-production wellheads. The loss of irrigation ditches and water impacted local ranches and residents.

An intense moisture-laden storm combined with a push of unseasonably cold air from Canada to produce blizzard conditions and very heavy snowfall over eastern Wyoming, western South Dakota, and the adjacent Plains states. A chilling rain turned to snow, accompanied by 50-70 mph gusts, causing extensive livestock mortality, estimated at 60,000-100,000 head of cattle across the region. The western Black Hills in Crook County received up to 5 feet of snow.

A near-stationary weather system funneled copious subtropical moisture into the Front Range, leading to one-week rainfall totals of 10-18" over a large area. Creeks and rivers from the Wyoming border to Colorado Springs flooded, with the worst flooding on the Big Thompson River, Little Thompson River, St. Vrain Creek, Lefthand Creek, and Coal Creek. Over 20,000 homes were damaged or destroyed. Incredible and widespread damage to civil infrastructure (roads, bridges, water conveyance and treatment) on the Front Range.

"Riverside Park Levee, Evans, Weld County, 2013: The Riverside Park levee failed in Evans during the September 2013 flooding. The floodwaters created a 70-foot gap in the levee. The flood put the sewage treatment plant out of operation, leaving residents unable to shower or flush their toilets for over a week." - CO Hazard Mitigation Plan 2018-2023

The Black Forest Fire ignited during moderate drought conditions, on a red-flag-warning day where temperatures were in the 90s F and relative humidity was below 10%. It rapidly spread through densely forested suburban neighborhoods, destroying 511 homes in all, and burning over 14,000 acres. The second most destructive wildfire in Colorado history in terms of homes lost, behind the Marshall Fire in 2021.

"The West Fork Fire Complex (110,405 acres) resulted after three lightning-sparked fires connected with one another in the Weminuche Wilderness area northeast of Pagosa Springs in southwestern Colorado. The fire was fueled by beetle kill trees and a dry summer. Firefighters were assisted when a monsoon brought needed moisture to the area." - 9News

"The avalanche was quite large and engulfed the entire group from above at approximately 10:15am. The avalanche pushed all group members between 5 and 20 feet into the Sheep Creek gully. Five of the six members of the group were completely buried. The survivor was 3rd in line at the time of the accident, and was partially buried in very close proximity (touching) to the two group members in the front of the line. The survivor came to rest in an upright semi-seated position with his lower left arm free, and his face very near the surface. He was able to clear the snow from his face, and at that point could breathe freely. He then began slowly moving snow away from his face and head and trying to free his right arm from the snow. The survivor continued to yell for help, but to no avail, as there was no one left unburied to hear him and no other people in the area. The survivor was stranded in this position for approximately 4 hours before rescuers arrived at the scene." - Colorado Avalanche Information Center

"On the evening of 10 April 2013 (MDT) a massive landslide occurred at the Bingham Canyon copper mine near Salt Lake City, Utah, USA. The northeastern wall of the 970-m-deep pit collapsed in two distinct episodes that were each sudden, lasting ~90 seconds, but separated in time by ~1.5 hours. In total, ~65 million cubic meters of material was deposited, making the cumulative event likely the largest non-volcanic landslide to have occurred in North America in modern times. Fortunately, there were no fatalities or injuries." - GSA Today

Laub Detention Dam. Cause of failure: Heavy rainfall. $4.2M (2022 dollars).

"Laub Detention Dam failed on September 11, 2012. A severe storm with heavy rainfall occurred prior to the failure. Numerous homes, businesses and roads were damaged. No lives were lost. A Presidential Disaster Declaration was declared for Washington County on November 3, 2012. The Dam was rebuilt in 2013 and was renamed "Tuacahn Wash Lower Detention Basin." - Utah DEM

The Arapahoe Fire was started by lightning on July 27th and burned 98,115 acres before it was contained on August 23rd. The fire destroyed 30 homes and damaged 8 others. Firefighters struggled to contain the fire during extremely dry conditions and erratic winds.