The Boulder City Council has unanimously approved using 4.1 acres of city open space land for flood mitigation near the controversial CU South property along South Boulder Creek. The vote brings the city closer to breaking ground on its largest flood project, which involves building a detention wall along U.S. 36 to prevent floodwaters from overtopping the highway.
The city council’s decision allows for the permanent “disposal” of 2.2 acres of city open space for the flood project, with an additional 1.9 acres to be used temporarily during construction.
The vote could be the final pivotal decision by the Boulder City Council on the future of the flood mitigation project. Several councilmembers described it as a significant milestone in a process spanning decades.
“This has been a very long road,” Mayor Aaron Brockett said during the meeting. “With this, we come to the end of at least the discretionary part and move to the implementation of the flood mitigation project.”
The project aims to remove 2,300 Boulderites from the 100-year floodplain and protect some 1,100 homes. At its March 13 meeting, the Open Space Board of Trustees also voted unanimously to approve the land disposal.
“There’s some finality to this,” Councilmember Matt Benjamin said during the city council meeting. “Tonight, we have provided 2,300 Boulder residents a better chance to sleep at night.”
The disposal — a formal process required to build on protected city open space — is an important but incremental step toward getting the long-planned, $64 million flood project built. The city still needs permits from the Federal Emergency Management Agency and the Colorado Department of Transportation, to name a few. On the design side, the city recently released its 60% design and is working towards a 90% update. The latest estimate shows construction starting in early 2025.
The project has long been controversial due to its location near the CU South property, which is owned by the University of Colorado Boulder. Talks of CU developing this land have been ongoing since 1996, when the university purchased it from a gravel mining company. For years, the land has been kept open to the public. Residents have pushed three ballot measures seeking to prevent development. All were voted down.
Under a 2021 annexation agreement between the city and CU Boulder, the university granted permission for the city to build a concrete spillway along U.S. 36. In exchange, the city is allowing the university to access city water and utilities and build approximately 1,100 units of housing for non-first-year students and faculty, as well as facilities, offices, commercial and retail space, and infrastructure enhancements including a new multi-use path and bus station.
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Opponents of the flood project have long voiced frustration that the plan is tied to annexing the property into city limits and allowing CU to develop the land, which is cherished by many who use it for recreation.
Recognizing this, at their March 13 meeting, the Open Space Board of trustees voted 4-1 to encourage “public recreational access be restored as soon as practicable” to the project area, according to the board’s statement. The statement also says the area “represents not only a great opportunity for riparian restoration and reconnection of the South Boulder Creek floodplain” but also for “the public to observe, at close range, the restoration of floodplain and the native ecosystem.”
The talk of floodplain restoration reflects the unique opportunity of the South Boulder Creek project area. Because it’s mostly undeveloped, the city plans to remove a levee originally built to keep floodwaters out of the former gravel mines, allowing those waters to flow more naturally as they once did.
The city would also gain some open space. As part of the annexation agreement, the city will acquire about 119 acres of land from CU that is currently in the historic South Boulder Creek floodplain and designate it as city open space. Dan Burke, the director of Open Space and Mountain Parks, told councilmembers during a meeting in February 2023 that this land acquisition will enable the city “to undertake one of the largest wetland restoration projects in the City of Boulder’s history.”
Opponents of the land disposal have argued it is premature for the city to relinquish the approximate 4.1 acres of open space without having secured all the necessary permits to complete the project. The Colorado Department of Transportation, for example, still must approve using the U.S. 36 corridor for the flood detention wall. The city has responded to this concern by stating that under the formal land transfer request, the acres would revert to Open Space and Mountain Parks management if the project is not fully permitted or built.
Critics of the South Boulder Creek flood mitigation project have also questioned its adequacy. They argue that relying on a 100-year flood standard is insufficient given the expected increase in flood intensity and frequency due to climate change, advocating instead for 500-year flood protection.
The city has acknowledged that while the project won’t prevent 500-year flooding, it would reduce floodwaters overtopping U.S. 36 and flowing into vulnerable communities. The city originally considered a 500-year standard, but several hurdles — including potential pushback from CDOT and the need for more open space — led the city council to agree to a 100-year plan.
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