All Local, All The Time
All Local, All The Time
Flooded bridge by the Greenbriar Inn at Highway 36 after the 2013 flood.
After the flood, some major improvements were made to the culverts in the same area.
Niwot High School baseball fields during the 2013 flood.
Niwot High School baseball fields after the 2013 flood.
Flooded view of Oxford Road from 41st Street.
View of Oxford Road at 41st Street after the 2013 flood cleared.
On Sept. 9, 2013, a severe flood started along Colorado's Front Range, particularly impacting Boulder County. The flood continued through Sept. 15, 2024, causing widespread damage. The flood was triggered by an unusual amount of rainfall, surpassing what is expected in a 500-year flood event.
A 500-year flood event means there is a 0.2% chance of such a flood happening in any given year. The 0.2% chance is a statistical term that describes the recurrence interval of floods, not a timeline that indicates when a flood will happen. Remarkably, a year's worth of rain fell over that week in 2013, matching the region's typical annual rainfall. Boulder County's rainfall can vary from 18 to 20 inches per year.
The 2013 flood event was even more unusual because of both the geologic and hydrologic contributions. Steep mountain slopes collapsed, with thousands of tons of sediment, large boulders and trees reaching the valley floor, flooding streams. The debris included sediment, boulders, trees, roadways, and buildings. Temporary dams were formed, and the water backed up until a failure point was reached, releasing a surge of water which caused further damage downstream, according to The Mile High Flood District's Flood Hazard News, formerly Urban Drainage Flood Control District.
Many news reports and articles stated that Colorado had experienced a 100-year or 1,000-year flood, but the data varied widely. Many peak discharge estimates fell below the 100-year threshold, while others exceeded the 500-year threshold. The classification depended on the contributing watershed and rainfall.
The September 2013 flood was extreme, but there have been worse floods, such as the South Platte River flood in 1965, which remains Denver's worst flood on record. Many people have forgotten the Big Thompson Canyon flood in 1976, which occurred during Colorado's Centennial year, causing $35 million in damages, and claiming 140 lives.
The nation saw the National Flood Insurance Act passed in 1968, creating the National Flood Insurance Program, which provided available and affordable flood insurance and started incentivizing best practices in flood plain management. This was followed by the Flood Disaster Protection Act in 1973, which made the purchase of flood insurance mandatory for properties located in specific flood hazard areas.
How will climate change impact future floods? The Climate Risk and Resilience Portal was created to look at how climate change can potentially impact the nation, including Colorado. The Center for Climate Resilience and Decision Science at Argonne National Laboratory in collaboration with AT&T, the Department of Homeland Security's Federal Emergency Management Agency (FEMA), and the U.S. Department of Energy Grid Deployment Office is providing data to prepare for future natural disasters.
Many changes have occurred since the Big Thompson Canyon 1976 flood, resulting in fewer deaths from the 2013 flood. Many factors prevented increased damage and loss of lives in the 2013 flood event, including 30-plus years of preparing for the "next Big Thompson Canyon flash flood."
Some of these factors included advances in communication technologies, which were limited in 1976; early advisories given to local authorities concerning developing threats, which was chaotic in 1976; early flood warnings; new roadway signage directing people to climb to higher ground; new technology for real-time rainfall and stream level information; and radar and other storm tracking technologies.
Ironically, members of the Colorado Association of Stormwater and Floodplain Managers (CASFM) were attending its annual conference in Steamboat Springs during the September 2013 flood. CASFM is the Colorado arm of The Association of State Floodplain Managers (ASFPM), a scientific and educational nonprofit organization dedicated to reducing the impact of flooding and stormwater management issues. With the unfolding of the stationary front parked along the Front Range in 2013, the conference ended abruptly, with all the managers returning to their respective government entities to help their communities.
Time will tell if lessons from the 2013 flood will reduce the impacts of the next Colorado flood event.
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