Flash Flood Alley Segements

 

Boulder, Colorado: High Hazard Flood Area

The town of Boulder, Colorado, lies in an area subject to very rapid runoff and an overall region that has experienced many floods. There is one particular section of town (very near the center of the city) that is known to be a high-hazard zone with respect to both how quickly and violently a flash flood could impact the area.

Helpful Links:

A background on floods in the Boulder Creek Drainage Basin

Significant Front Range Floods

City of Boulder information on flood events

A USGS report on Major Floods and Droughts in Colorado

This scene is from the City of Boulder Flood Hazard Map (enlarged view)

Boulder's High Hazard Zone

There is no doubt that this area will eventually be devastated by a large flood. Perhaps the biggest consideration is that it could happen in just a few hours.

The area highlighted to the left shows both the "100-year floodplain" (in blue) and the area that is expected to have the deepest and most powerful current (in red). This area includes City of Boulder facilities, University of Colorado married student housing, many residences, businesses and Boulder High School. Anyone living in or near this area should be prepared to evacuate quickly or at least move to a higher floor in a safe building. Many other additional precautions for life and property safety can be found throughout this web site.

The 1894 flood devastated downtown Boulder with most of the current tracking down what is now Canyon Street. The eventual repeat flood of this magnitude may well cause hundreds of millions of dollars of damage.

May 31 - June 2,1894

Heavy rains fell all along the Front Range and were particularly heavy in the Boulder and South Boulder Creek basins. Rainfall records for a 96-hour period showed that the mountain drainage area received from 4.5 to 6 inches of precipitation. The mountain rainfall, combined with the snowmelt runoff to produce the greatest flood known in Boulder, which came roaring down the valley during the night of 30 May 1894. Buildings, bridges, and even long sections of roads and railroads were washed away.

Estimated flow on Boulder Creek at 4th Street : 11,000 to 13,500 cfs (cubic feet per second)