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  • Floodplain Map
  • Creeks of Boulder
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Boulder Flood Info

* Please note, this page and all the pages linked through this page are in the process of being updated. If you are unable to locate specific information, please contact Laurel Olsen or call 303.441.3203. Thank you for your patience. 


BE AWARE | BE VIGILENT | BE SAFE - It's currently flood season, are you flood prepared?

April through September is considered "flood season" along the Front Range. Are you ready for the next event? 

During flood season, the Office of Emergency Management will test the emergency sirens located throughout the city/county. Tests of this system occur on the first Monday of each month during flood season and can be heard at 10 a.m. and again at 7 p.m. The purpose of the test is to verify the system is working as intended (it is meant to be heard by community members outdoors who may not have immediate access to emergency warnings otherwise. They are not intended to be heard necessarily by community members located inside.)

Flood Information 

The city of Boulder rests at the base of the Rocky Mountain Foothills and is home to Boulder Creek, its 14 tributaries and Boulder Slough (diverted water from Boulder Creek to satisfy irrigation company water rights). Due to its geographic location, the city of Boulder has the highest risk of flash flooding in the state of Colorado. 

Many neighborhoods throughout the city experience flooding during storm events, and some are at a higher risk to extreme flooding because they are located near a major drainageway. The City of Boulder encourages all residents to be aware of their flood risk and to take the necessary precautions to help protect life and property. 

To learn more about the City of Boulder's flood management projects and programs review this section:

In 2020, the city has embarked on updating the Comprehensive Stormwater and Flood Management Master Plan, the policy which guides flood management, stormwater drainage, and stormwater quality in the city. 


Stay Connected

Questions? Request Flood Information

Sign up for free emergency alerts at BoCo911Alert.com.


Additional Links and Resources

Flood Mitigation   Boulders Greenways   September 2013 Flood  

Irrigation Ditches

Irrigation ditches are manmade channels that deliver water to homes, farms, industries and other human uses. Most irrigation ditches divert water from natural creeks and rivers and bring it to other areas. Irrigation ditches also can carry stormwater run-off from surrounding neighborhoods and can be a source of flooding in those neighborhoods. Most irrigation ditches are privately owned enterprises.