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Boulder Creek Floodplain Mapping Update

Boulder Creek Floodplain Mapping Update

The Boulder Creek Floodplain Mapping Study evaluated the floodplain from the area west of 61st Street, upstream to the mouth of Boulder Canyon, west of Boulder city limits. The study area encompassed a reach length of five and a half miles.

Based on this study, the city has developed new floodplain maps for Boulder Creek that would replace both the Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM) and the City of Boulder floodplain map.

The proposed floodplain maps were developed based on:

  • updated topographic data,
  • updated floodplain, floodway and high-hazard zone boundaries, and
  • city improvements that help reduce flooding along Boulder Creek.


The final project documentation was submitted to FEMA for review and approval in September 2013. In November 2013, FEMA indicated that they accepted the results of the study and will be adopting the new mapping through the Physical Map Revision process, which is expected to take several months. The process was delayed due to the September 2013 flooding.  The final maps are anticipated to be effective in the fall of 2016, although this schedule is subject to change.

Previous Meetings

City Council Public Hearing - Tuesday, Sept. 18, 2012
The Utilities Division provided City Council with an update on the current status of the Boulder Creek Floodplain Mapping Update and requested approval of the study. City Council voted unanimously to approve the floodplain mapping study and directed staff to submit the study to the FEMA for review and adoption.

Planning Board Public Hearing - March 15, 2012
The Planning Board voted 4-0 to recommend approval of the flood mapping study.

Water Resources Advisory Board (WRAB) Public Hearing - Feb. 27, 2012
The WRAB voted 4-0 to recommend approval of the flood mapping study.

Study Results

The final report and all attachments, including photos and maps, are available under the "Technical Report" links on this webpage.

To see the revisions to the floodplain maps, select the "Floodplain Map (interactive)" link. The revised Boulder Creek mapping can be viewed by selecting "Revised Boulder Creek Flood Layers" and then choose different layers for viewing.

Please Note: These maps may not be completely comprehensive due to data limitations. Staff will continue to make enhancements and modifications as needed.

For property-specific information about the land development requirements for all floodplain zones, contact Planning & Development Services at 303-441-1880 or

Please note: Boulder Slough hydraulic modeling was not included  in this mapping effort to allow the project team to focus on the more critical work associated with the Boulder Creek floodplain. The Boulder Slough is the old-flow path of Boulder Creek that separates from the Boulder Creek floodplain at approximately 17th Street and joins the South Goose Creek floodplain east of Foothills Parkway. The Boulder Slough floodplain is being studied as a separate effort.


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