boulder flood.

Boulder faces the largest threat from flooding of any city in Colorado. Steep mountain streams feed the creeks that run through the center of the city and each of these is vulnerable to flash flooding. Extensive rainfall caused all of these streams to flood in September 2013.

Large amounts of sediment, ranging from small pieces of clay to boulders up to three feet in diameter, were transported out of neighboring canyons and deposited in Boulder Creek. The flood waters were so powerful that many water channels relocated causing $2 billion in property damage.

The degree of damage is each location is indicated by the length of cuts. In some locations, flood water feel short of 100-year and 500-year floddlines. These areas are indicated with more space between cuts to show the potential future threat.

All data were taken from the City of Boulder Open Data Project. Additional information was provided by Wright Water Engineers.