Project Overview

The goal of this project is to protect public and private properties, reduce potential damages due to flooding and improve the condition of the creeks. The project aims to maximize natural features in the landscape and ecosystems, protect sections of the existing stream, and improve storm sewer systems to better withstand impacts from climate change.

The community and the city will be working together to rehabilitate the watershed through natural channel restoration, preservation, conservation and restoration of our waterways.

Project Timeline

Click the image below to expand the project timeline.

Goose Creek Project Timeline


  • Protect life and property
  • Reduce high hazard zones and floodplains
  • Preserve the watershed and stabilize the streams
  • Accommodate precipitation from minor and major storms
  • Create resilience for the future


  • Mimic natural stream channels with engineering
  • Create slope and depth variability in the stream bed
  • Repair stream banks
  • Reduce bank sediment by implementing stabilization and natural channel design

Project Outcomes

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

Goose Creek Project Outcomes

Flood Mitigation Plan

Click the image below to expand the Flood Mitigation Plan.

Flood Mitigation Plan

Nature-Based Design

The city strives to help protect people, places, property, and ecosystems in a way that builds resilience and is consistent with community values.

Community Engagement

Q4 2023 - Community Meeting - Upper Goose Creek and Twomile Creek Community Meeting. 6 to 7 p.m. on Nov. 15, 2023 at Foothill Elementary School.

The purpose of the meeting was to provide updates on the Upper Goose and Twomile Canyon Creek (UGT) Flood Mitigation Plan and timeline for next steps.

May 18, 2023 - City Council, Public Hearing - Staff presented the plan to City Council for approval.

March 20, 2023 - WRAB Meeting
The Water Resources Advisory Board made their recommendation to send the plan to City Council. Pending City Council approval, concept and preliminary design will move forward.

Dec. 7, 2022 - Information Session
On Dec. 7, 2022 we held an information session to meet the new project manager for the Upper Goose & Twomile Canyon Creek flood mitigation project, learn where we are in the project process and ask questions.

Frequently Asked Questions

When will construction begin? Once the design alternatives are selected, detailed construction plans, cost estimates, bids from contractors and construction schedules will be prepared. Construction on some reaches is tentatively set to begin in 2026. Property owners and community members will be fully informed before construction.

How can I stay informed on the Goose Creek Reach 6 project? Following City Council approval of the Upper Goose Creek and Twomile Canyon Creek Flood Mitigation Plan on May 18, 2023, the plan has moved into the design and construction phase where more specific details can be developed and discussed with the community. For the most up to date information and opportunities for continued community engagement, please visit the website and sign up for email updates. You can also email specific questions to

Were community preferences and concerns considered, and will there be more opportunities for community engagement as the mitigation plan proceeds? Yes. The city understands the continued concerns of the community and the desire for details. As the project proceeds the city will be informing affected property owners about the configuration of the improvements, acquiring drainage easements along the necessary reaches, and providing private property protection during construction.

What kind of disruption/interruption/commotion should neighbors expect behind his property and for what length of time as mitigation moves forward? The city recognizes this is a huge concern and will be fully transparent and have discussions with owners as the plans and construction schedules are put together. More detail will be provided for each property owner once plans are finalized as we work through the design and continue to receive feedback through engagement in the development of the plans.

Could you please provide more information about the possible alternatives under consideration for the implementation of "UGC Reach 6"? Specifically, I’d like to understand why is the city recommending improved conveyance of Goose Creek instead of piping flood flows under the roadway? The City of Boulder prioritizes a nature-based approach to flood mitigation citywide as it restores natural stream functionality, increases resilience to flooding events, enhances urban ecosystems and supports the city’s climate goals. Such an approach is in alignment with national trends, industry standards, and the 2022 Comprehensive Flood and Stormwater Master Plan (see excerpt below). The current recommendation for Upper Goose Creek Reach 6 proposes improving channel conveyance and restoring the stream channel using this nature-based design approach.

Previous investigation of a piped alternative under Edgewood indicated that such an approach was not viable. However, given community interest, the team will take another look at a more detailed design to see what it would take to route flood flows under the road and share that report with the community when it has become available.

Is there still an alternative to convey Twomile Canyon Creek flow down Floral Drive to reduce flows along Goose Creek? Yes. The Floral Drive alternative has been included in the flood mitigation plan and is currently being evaluated in more detail. City council communicated a preference for the Floral Drive alternative and additional design details will be provided to the community when we have more information available.

Will there be public access along Goose Creek Reach 6 as part of the project? No. Public access is not included in the Goose Creek flood mitigation plan for Reach 6. There is also no reference to future public access in the Transportation Master Plan or Greenways Master Plan, which all generally guide future city projects that have been approved by council.

What are the details in the mitigation plan for the size of the culverts, and the width and configuration of the proposed channels, and what will the channels look like? The design of the details will not occur until after the mitigation plan is approved by City Council, and as that process moves forward, the community will be informed of the design as it is developed. More detail will be provided for each property owner once plans are finalized as we work through the design and continue to receive feedback through engagement in the development of the plans.

Was any consideration given to utilizing additional street conveyance down Iris, Edgewood, and other streets rather than the alternatives shown? The streets collect water in a storm sewer system that is not sized for a major storm event, so streets are currently conveying excess stormwater. Increasing the depth of water even more could result in turning them into high hazard zones, jeopardizing life safety and emergency access.

How were the alternatives scored to make the decisions presented in the mitigation plan? After the results of the community outreach to create alternatives for the various reaches of the UGT creek system, the community was encouraged to vote on preferences. This information was combined with the community values described in the CFS, and the results were tabulated and given scores to determine the priorities and preferences in a general sense for the mitigation plan.

Do the mitigation plans include things like debris and blockages? Debris, damage, blockages and clogging are always considerations for the design of storm sewers, channels, box culverts, and all the elements of flood conveyance. The hydraulic model includes blockages ranging from 10% to 100%, depending on conditions and the storm event.

Will the revised floodplains be constructed with concrete-lined channels? No. There are no plans to construct concrete-lined channels, as this is contrary to the current thinking, guidelines, wetland regulations, water quality considerations and desires of both the city and the community. The intent is to construct sustainable, attractive, re-vegetated stream corridors that encourage natural riparian habitats and wildlife ecosystems.

Why is flow from Twomile Canyon Creek being directed toward Goose Creek along Edgewood, with modifications to Goose Creek on that reach, and won’t that increase the flood risk to those areas, causing those homes to be flooded? Historically, water flows overland from Twomile Canyon Creek toward Goose Creek, and it will continue to do so, regardless of improvements upstream. The city will not revise any floodplain to put any homes at further risk from additional flooding than before, and reconfiguration is intended to lower the water surface elevation in a flood event, removing homes from the floodplain where possible, decreasing the overall risk for homes. Even though this portion of the creek did not flood significantly in 2013, flooding could occur in the future from the more typical flood event.

If Goose Creek is widened between 19th and 24th St. are the engineers considering the difficulties and costs to stabilize the existing steep slope and protect the homes on the south side of the creek? Yes. Portions of the existing slope are already experiencing severe erosion and deteriorating trees that can lose the root structure and put the area at risk of further slope failures. A detailed and thorough geotechnical investigation to design appropriate slope stability is a key element of the improvements to this reach of Goose Creek.

Why are multiple paths shown on the mitigation plan for Twomile Canyon Creek south of Linden Ave.? The multiple paths shown on the mitigation plan represent the problem. The loss over time of the original creek channel has caused the flow to deviate from the main channel of Twomile Canyon Creek into other pathways, meandering through local streets and neighborhoods south of Linden both east and west of Broadway until it re-enters Goose Creek, and is joined by flow from Elmer’s Twomile Creek, just east of Valmont and 28th. This results in substantial flooding of those streets and residential areas.

If there is not enough room for the “100-year” channel, why doesn’t the city use imminent domain law to acquire necessary land for public good between Linden and Broadway instead of designing the channel for less than “100 -year” flood conveyance? Respecting the wishes of the community and the residents of the neighborhood is extremely important. Forcibly taking over property is very rare. The city will negotiate with the private property owners to acquire drainage easements prior to any final plans or construction. In some instances, private property owners are willing to vacate their property and sell it to the city, and when appropriate, the city will consider purchasing the property.

Will Twomile Canyon Creek mitigation east of Broadway handle the “100-year” flood? The proposed mitigation plan will convey the “100-year” flood in this reach to 19th Street, with a combination of an open channel along Iris Avenue and storm sewer improvements along 13th Street, Hawthorn Avenue, 16th Street, and Grape Avenue. The exact alignment and combination will be determined in the next phase of design development.

How will impacts to environmental resources (wildlife, vegetation, wetlands, etc.) in Goose Creek Reach 6 be considered? Any work in streams requires extensive permitting and oversight from Federal, State and local agencies, including the Army Corps of Engineers, US Fish and Wildlife, Colorado Department of Public Health and the City of Boulder. Prior to any construction, permits for impacts and any mitigation will need to be approved by these agencies. Agency findings and mitigation strategies will be shared with the community on the project website

Is the city considering the value of Upper Goose and Twomile Canyon Creek as a wildlife corridor? Yes, absolutely. The city is committed to environmental stewardship and protection of streams and riparian wildlife areas, which are valuable ecological and community resources. Restoration will include removal of non-native vegetation and re-introduction of native vegetation to support the natural ecological environment, the return of native wildlife, and creation of more sustainable habitat.

Has the City accounted for the past and possible future wildfires in the Twomile Canyon Creek watershed? The city is aware that wildfires increase the chances of flooding from debris and additional runoff. This is even more of a challenge given that finding adequate space is already difficult. The majority of the fire risk area is in the watershed located west of the city limits of Boulder, in Boulder County. Additional information for the County can be found here:
Boulder County Wildfires (
Creek Recovery & Restoration Program - Boulder County

In the 2013 flood event, some areas of the city experienced extensive flooding and damage, and other areas did not. What was the final declaration for the 2013 flood event related to both Upper Goose Creek and Twomile Canyon Creek? Some reports declared it a “100-year” event, and some did not. In September 2013 Boulder and the uphill watershed received up to 18 inches of rain in a few days. This exceeded the total precipitation normally received in an entire year. Some areas of Boulder received the “100-year” intensity of precipitation, and others did not, resulting in unpredicted and varying flood levels. The flood designations vary depending on the location and duration considered.