Fourmile Canyon Creek
Fourmile Canyon Creek beginning to overflow the underpass at Broadway during the 2013 flood event.
Fourmile Canyon Creek, in north Boulder, begins in the foothills west of Boulder, has a tributary watershed area of just over ten square miles and flows for approximately 11 miles before entering Boulder Creek. It is part of Boulder’s greenways system, and is included in flood mitigation studies and projects.
Most of the western half of Fourmile Canyon Creek is located within city limits, apart from the the section located in Boulder County, located between 19th Street and 26th Street. The eastern half is located primarily outside the city limits in Boulder County.
Review the interactive map of the creeks of Boulder .
Fourmile Canyon Creek Projects
Spring 2020 Update: advanced preparation work (potholing and utility relocations) began in April 2020. Construction is anticipated to begin in Fall 2020.
As part of the North Broadway (Violet to US 36) Reconstruction project, the City of Boulder will be adding features to the underpass at Fourmile Canyon Creek to increase flood capacity to a 50-year flood event .
The underpass will be at full new capacity once other improvements are made downstream. The new underpass at Broadway will require a flow restriction device to be installed to mimic current flood conditions until the downstream improvements are made.
Details on how the flow restriction will be accomplished are pending hydraulic design.
The project on Fourmile Canyon Creek and 19th Street is intended to improve safety and accessibility to Crest View Elementary School, and create additional flood capacity under the roadway.
Preliminary design is currently underway, and final design is anticipated to be completed by the end of 2021, with a 2-year construction period to follow.
Funding for transportation components of the project will come from the 2017 Community, Culture and Safety Tax extension. A Community and Environmental Assessment Process (CEAP) for Fourmile Canyon Creek east of 19th Street was completed in March 2012 and the city has hired a consultant to complete a design for the improvements for this area.
Additionally, the project team is coordinating improvements with the Capital Projects workgroup, which is leading design for the 19th Street Multimodal Improvements Project, expected to begin construction the end of 2021/early 2022.
Jan 16, 2020 - North Broadway (Violet to US36) Reconstruction Project Open House at Crest View Elementary
- City staff and consultants were on hand to answer questions about the Broadway Reconstruction Project.
- One of the stations at the open house featured information on the improvements to Fourmile Canyon Creek.
Nov. 21, 2019 - North Boulder Transportation Projects Open House at Crest View Elementary
- City staff and consultants were on hand to answer questions about several transportation projects in north Boulder.
- One of the stations at the open house featured information on the improvements to Fourmile Canyon Creek.
June 6, 2019 - North Broadway (Violet to US36) Reconstruction Project Open House at Crest View Elementary
- City staff and consultants were on hand to answer questions about the project.
- One of the stations at the open house featured information on the improvements to Fourmile Canyon Creek at Broadway as part of the overall project design.
Fourmile Canyon Creek Mitigation Planning Information
The City of Boulder finalized the Fourmile Canyon Creek and Wonderland Creek Major Drainageway Plan 
in 2011. Minor updates were added in 2017.
A Community and Environmental Assessment Process (CEAP) is a formal review process to assess potential impacts of project alternatives in order to inform the selection and refinement of a preferred alternative.
The CEAP provides an opportunity to balance multiple community goals by assessing a project against the policies outlined in the Boulder Valley Comprehensive Plan and department master plans.
The Fourmile 19th - 22nd Streets CEAP was adopted by city council in April 2012.