After voters rejected a ballot measure in the last election that would have halted the South Boulder Creek flood mitigation project at the CU South property, what is the project’s status a year later?

According to the latest update from city officials, it’s still on track to break ground in late 2024, though potential permitting challenges could cause delays.

City staff provided the Open Space Board of Trustees a design update on Oct. 11. The open space board received the update instead of the city council because the South Boulder Creek flood mitigation project, designed to protect 2,300 residents from a future “100-year flood,” will require the use of open space for building a flood detention wall. 

Boulder is protective of its open space, and to repurpose land, city staff have to get the open space board’s approval. The Oct. 11 presentation was for a 60% design, meaning staff have moved past the conceptual phase and are tackling nuances of the project. At this stage, staff say they need roughly 4.7 acres to be approved by the open space board for the construction of a flood wall. Previous designs had the open space requirement at 5.1 acres.

“We’re now at the level of design where we have a pretty good handle on what the footprint of the project is going to be,” Joe Taddeucci, director of the city’s Utilities Department, said in an interview. Further reductions in open space are possible as plans are finalized, he added.

How the flood mitigation project would ideally work in a 100-year flood. The roads seen are US 36 at its intersection with Foothills Parkway. Courtesy of the City of Boulder

The South Boulder Creek flood mitigation project is the city’s highest-priority flood project out of 37 planned for the next three decades. Long in the making, the project gained urgency after the devastating Boulder flood a decade ago. A concrete flood detention wall along US 36 will keep future 100-year floodwaters from overtopping onto the highway. And an earthen embankment near the highway’s intersection with Foothills Parkway will prevent flooding from reaching nearby neighborhoods. Detained water will accumulate on the property before pipes take it under US 36 and let it continue safely downstream. 

Nothing has been constructed yet, because the city needs access to protected open space to do so.

In the first quarter 2024, Taddeucci said city staff will make a formal request for this “disposal” of open space. Of the 4.7 acres, 3.7 would be for permanent use and 1 acre temporary. After that, the public will have a chance to weigh in before the board makes a decision.

Even though the Oct. 11 meeting was not a public hearing, several people spoke out against the project, offering a preview of the challenges to come. Steven Telleen of Save South Boulder, a group opposing the South Boulder Creek flood project, articulated one of the main arguments used by detractors: The city needs a swath of permits and agreements before it can begin construction of the mitigation project, and there’s no guarantee it will get them. 

“It would be negligent for the [open space] board to approve any open space disposal until these requirements are formally approved,” he told trustees at the meeting. 

The city still needs dam safety approval from the State Engineer’s Office and a floodplain review from the Federal Emergency Management Agency. It also needs a permit from CDOT to work in its US 36 corridor. 

Opponents of the project point to the CDOT permit as one the city may have to fight for, with no guarantee of getting it. 

Taddeucci said a letter from CDOT several years ago indicated the department did not support the project encroaching onto the US 36 corridor. But he said “the relationship with CDOT and the design concept has evolved a ton since then.”

“If they were fundamentally opposed and had no intention of approving the concept we’re bringing forward, there’s no way an entity like that would be engaging with us and making these micro approvals along the way,” he said.

The chair of the open space board, Dave Kuntz, said, “My preference would be to have most of the permits approved or in final approval” before the board disposed of any open space land.

To address this concern, one approach could be to include “reversionary language” in the disposal process, a board member said. This means if the open space board votes to allow the use of open space, but the city can’t secure the necessary permits and agreements, the land would revert back to open space. 

“I’m just concerned that we dispose of some open space and are left holding the bag saying, ‘Why did we do that?’” Kuntz replied. “We should have some way to protect ourselves. And we do.”

Open space disposal key battleground over CU South

The South Boulder flood mitigation project is slated to be among the first projects built at the CU South site, thanks to the 2021 annexation deal between the University of Colorado Boulder and the city, which also paves the way for student and faculty housing and academic facilities. If, for whatever reason, the flood project does not get built, the annexation agreement allows the city to annul the entire deal with the university.

For that reason, the flood project and the open space “disposal” process have long been seen as pivotal battlegrounds over the property.

Read: Decades of ‘what-ifs’: The history of CU South leaves many wondering what could have been

In April 2022, city staff presented initial designs for the $63 million flood project to the Boulder City Council. Since then, they have been fine-tuning the project, progressing from 30% to 60% completion.

The main changes from the 30% design to the 60% design relate to the wall and the outlet piping, both of which reduce the burden on open space.

By moving the flood wall that would border US 36 closer to the highway, less open space is needed. Same with piping that moves water out of the detention pond and under US 36. In an earlier design, the path of that piping would have necessitated construction on open space. 

In the 60% design, staff also delved deeper into the project’s details. The flood detention wall, for instance, will be concrete. In the 30% phase, the focus was on ensuring its structural integrity. But in the 60% phase, staff also considered the wall’s appearance.

One of the concerns is the possibility that a wall of concrete along US 36 would attract graffiti. “We’ve been looking at alternatives to have [the wall] blend more naturally into the landscape,” said Brandon Coleman, a stormwater engineer for the city and the project manager for the mitigation effort.

One way city staff suggested lessening the amount of concrete exposed to potential vandalism was backfilling against the flood detention wall. Courtesy of City of Boulder

To deter potential vandalism, staff presented an option for backfilling against the wall on the US 36 side, so commuters will not see a slab of manufactured stone, but instead a slope of grass and other vegetation. 

An ongoing concern for some community members is the limits of a 100-year flood design.  A 100-year flood means flooding has a 1% chance of happening in any given year.

Opponents have often argued that instead of protecting against 100-year flooding, the city should be ready for 500-year floods that will become more frequent in a changing climate. The city considered this option several years ago, but found it infeasible. Yet at the open space board meeting, a board member asked what would happen in the case of a 500-year flood. 

“In a 500-year flood we would expect the facility to overtop along that spillway,” Coleman responded, adding that water would flow across US 36. “You would see a reduction in what 500-year flooding would be from existing conditions, but you would still see flooding.”

Tim Drugan is the climate and environment reporter for Boulder Reporting Lab, covering wildfires, water and other related topics. He is also the lead writer of BRL Today, our morning newsletter. Email:

Join the Conversation


  1. Thanks for the article! This is the only news about what’s going on at CU South that I’ve seen this year.

  2. This piece of CU’s land should NEVER be developed in any way. Let the natural floodplain work. More houses, more asphalt necessitates this flood wall. Stop licking around with nature!

    1. The “natural” floodplain was obliterated by gravel mining operations and when the land was recontoured when gravel mining ceased. The resulting floodplain can’t mitigate much if any effects of flooding.

  3. Thanks for this well done article. The only additional thing I would have liked to know is a cost estimate update.
    Because it was posted during the time of the local election swirl of news, please consider either featuring the article again at some point with minor updates or continually listing it in the ICYMI section.
    As a previous comment mentioned the article is the only one on the subject I have seen this year.

  4. Ditto, Michael. How much have we ALREADY thrown away on this boondoggle that may just be reversed once OSBT advises the CC for approval of the land disposal and the citizens reverse it in a ballot measure.

Leave a comment
Boulder Reporting Lab comments policy
All comments require an editor's review. BRL reserves the right to delete or turn off comments at any time. Please read our comments policy before commenting.

Your email address will not be published. Required fields are marked *