South Boulder Creek Flood Mitigation

The project aims to enhance the safety of community members and safeguard areas in the city prone to severe flooding from the South Boulder Creek drainageway.

The primary objective is to mitigate the adverse effects of floods, providing protection for community members and crucial infrastructure such as US-36 and Foothills Parkway, while minimizing impact on open space.

Since its approval by City Council in 2015, the city has collaborated with CU-Boulder and the Colorado Department of Transportation to develop flood mitigation solutions for an area affecting 2,300 community members and, 260 structures.

2026

In October 2025, CEI was selected to construct the first phase of the flood mitigation improvements for the South Boulder Creek Flood Mitigation project. In advance of construction on the site, CEI will be performing soil testing on the CU South site in February 2026. This will be minimally disruptive. We ask that community members and visitors use caution around the site, and to please follow detours to avoid any hazards presented by heavy equipment. More information will be available this spring.

2025

• City Council unanimously approved Ordinance 8690 on March 6, 2025, to authorize the city to issue $66 million dollars in Series 2025 Bonds for the first phase of the South Boulder Creek flood mitigation improvements. The bond proceeds will pay for the land acquisition and capital construction of flood mitigation infrastructure on and near the CU South site.
• Requests for Qualifications were published in March 2025, to solicit qualifications from the construction industry to construct Phase I of the South Boulder Creek flood mitigation improvements. The city anticipates qualifying a set of contractors and subsequently issuing construction bid documents this summer to solicit formal bids from qualified contractors.

2024

The February 2024 Draft Design Report is available upon request. Please reach out to Brandon Coleman to request materials or the attachments. Work on the design will continue through 2024.

March 21 - City Council Deliberations on Open Space Disposal, Spillway Annexation Second Reading, CU South Wetlands Ordinance Second Reading. Watch the meeting.

• Open Space Disposal approved nine to zero
• Spillway Annexation approved nine to zero
• CU South Wetlands Ordinance approved nine to zero

2023

Staff updated the Open Space Board of Trustees on the latest design on Oct. 11, 2023. View the agenda and listen to the meeting.

• 1938, 1969, & 2013 Floods
• 2015 Mitigation plan approved
• 2017 BVCP Updated
• 2017-2020 Conceptual Design
• 2019-2023 Preliminary Design
• 2024 Final Design
• 2026 Construction starts
  

• The main goal of this project is to mitigate the risk and damage to life and property caused by floods.
• Reduce high hazard zones and floodplains

• Create resilience for the future

• Avoid, minimize and/or mitigate impacts to the existing ecosystem
• Repair stream banks
• Reduce bank sediment by implementing stabilization and natural channel design

Incorporating natural channel restoration into flood mitigation projects can lead to a more vibrant, sustainable and resilient community and environment.

• Flood Mitigation: Restored natural channels can absorb excess water during heavy rainfall, reducing the risk of flooding in neighborhoods.
• Property Protection: Stabilized stream banks help prevent erosion, and protect homes and infrastructures located near streams.
• Improved Water Quality: Natural channel restoration filters out pollutants and sediments, leading to cleaner water.
• Educational Programs: These projects can serve as educational tools, promoting awareness about watershed health.
• Community Engagement: Natural channel restoration projects offer opportunities for community members to get involved through volunteer efforts, workshops, and collaborative planning.
• Environment: This project will avoid, minimize and/or mitigate impacts to the existing ecosystem.
• Wildlife Habitat: Restoring natural habitats can create homes for diverse wildlife species, enriching the local ecosystem and offering opportunities for wildlife observation.

There are an estimated 600 structures and 3,500 people in the South Boulder Creek floodplain within city limits. Flood mitigation studies have looked at several locations along the creek and through extensive public feedback and analysis, found the best location for flood detention was near US-36 on property owned by the University of Colorado-Boulder.

The purpose of flood mitigation, or lessening the damaging effects of a flood, is to provide protection for community members and major utilities and transportation infrastructure including US-36 and Foothills Parkway, while being the least impactful to open space. Since City Council approved the plan in 2015, city staff has been working collaboratively with CU-Boulder and the Colorado Department of Transportation to develop flood mitigation options for the area that will impact 2,300 community members, 260 structures and 1,100 homes.

Over the last 80 years, South Boulder Creek has flooded significantly six times, with overtopping of US-36 happening in 1969 and 2013. As a result, the city has been working to mitigate future flood impacts over the last decade. Learn about major milestones in the South Boulder Creek Flood Mitigation project.

The 2015 South Boulder Creek Flood Mitigation Plan is available on request. Please email floodprojects@bouldercolorado.gov for materials.

• University of Colorado - Boulder
• Mile High Flood District