Boulder Creek Floodplain Mapping Update

Introduction

The Boulder Creek Floodplain Mapping Study evaluated the floodplain from the area east of the confluence with Fourmile Canyon Creek, approximately three-quarters of a mile east of 61st Street, upstream to the mouth of Boulder Canyon west of Boulder's city limits. The study area encompassed a reach length of seven miles.

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

The proposed floodplain maps are being developed based on:

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

View the revised Boulder Creek floodplain maps.
Select the "Revised Boulder Creek Flood" map layer at the top right corner.

News/Status

The final project documentation was submitted to FEMA for review and approval in December 2012.

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

As a result of the proposed floodplain boundary changes, 106 buildings would no longer be affected by the 100-year floodplain, 72 buildings would be newly affected, and 574 buildings would remain in the floodplain. As the data is refined and public input is received, these numbers may change slightly, but the general trends will remain the same. Changes to the floodplain maps can affect flood insurance requirements - learn more.

The maps below indicate the differences in between the old and new floodplain designations.
(Zoom in to see the status of smaller structures.)

• Structure Status background information
•  Existing City vs. Proposed 500-year floodplain
• Existing City vs. Proposed conveyance zone
• Existing FEMA vs. Proposed 100-year floodplain
• Existing City vs. Proposed High Hazard Zone

Please Note: These maps may not be completely comprehensive due to data limitations. Staff will continue to make enhancements and modifications as the floodplain mapping process moves forward.

For property-specific information about the land development requirements for all floodplain zones, contact Planning & Development Services at 303-441-1880 or This e-mail address is being protected from spambots. You need JavaScript enabled to view it . 

• Land Development Fact Sheet
•  Effects of Disclosure of Flood-Liability on Residential Property Values

Related Documents

• Boulder Creek Floodplain Final Report
  • Appendix A - Supplemental Topographic Mapping for Boulder Creek
  • Appendix B - Vertical Datum Conversion Information
  • Appendix C - Boulder Creek Starting Water Surface Elevations and Upstream Tie-In Information
  • Appendix D - Field Recon Information for Boulder Creek
  • Appendix E - Tabular and Graphical WS Profiles for Boulder Creek
  • Appendix F - Flood Hazard Work Maps for Boulder Creek

    Index of Maps   Map 1  Map 2  Map 3  Map 4  Map 5  Map 6  Map 7  Map 8

    Map 9  Map 10  Map 11 Map 12 Map 13 Map 14  Map 15 Map 16  Map 17

  •  Original Hydrologic Report
  •  Hydrology Verification Report

Please note:  Boulder Slough hydraulic modeling has been suspended 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 17^_th Street and joins the South Goose Creek floodplain east of Foothills Parkway.

Contact Us

Use the form below or contact This e-mail address is being protected from spambots. You need JavaScript enabled to view it   at 303-441-3266 to ask questions and provide comments.

Last Updated on Friday, 15 February 2013 16:35