BOULDER, Colo. — Boulder is beginning a $76.5 million flood mitigation project on Monday that will close the 308-acre CU Boulder South site for three to five years in an effort to protect homes from major floods.
The project near Highway 36 and Table Mesa Drive will include a detention dam along the north and west edges of the CU Boulder South campus to store flood waters, a concrete spillway along Highway 36, an outlet tunnel beneath the highway, and a groundwater management system.
The city said a warehouse and tennis courts on the site will be demolished during the construction. The project is expected to protect 2,300 residents from flooding and is designed to prevent South Boulder Creek from overtopping Highway 36 during a flood.
Denver7 reporter Maggie Bryan spoke to residents about what this project will mean for the area in the video below:
The effort follows the devastating 2013 floods that struck the Front Range, including Boulder. Former Boulder Mayor Leslie Durgin remembers watching the floodwaters sweep through her neighborhood and the surrounding community.
"The flood waters were pouring across Highway 36. Cars were floating. People in the neighborhood were dashing out of their homes and trying to get out of the raging waters. It was a major flood, and this will prevent that from happening again," Durgin said.
However, some Boulder residents have been fighting to save the CU South site, saying the project will permanently alter the trails and open space they've loved for decades.
"We have been basically contesting the status of the dam construction and the overall destruction of this property," said resident Marki LeCompte. "All of us suffered from the effects of the 2013 flood. So we're not against flood mitigation at all. What we are against is a high hazard dam being built right across this property."
Dozens of people gathered at the open space on Sunday night to share memories about the land, including Renee St. Aubin.
"This morning there were so many cars, but yet when I was walking, I could be totally alone, and that's what this space does for you," she said.
The group Save South Boulder is calling for construction to be paused while its legal challenge against the project continues. The group's attorney, Randall Weiner, has petitioned the Colorado Supreme Court to hear the lawsuit challenging the city's use of stormwater utility fees to fund the flood mitigation project. He argues voters, not the city, should decide whether those fees can be used for the project. The petition follows the group's loss in state appeals court. Weiner said he expects to learn within the next three to six months whether the Supreme Court will take the case.
The CU Boulder South annexation agreement, approved by Boulder City Council in 2021, brought the site into Boulder's city limits. As part of the agreement, the university transferred about 155 acres to the city, including 119 acres that will become new permanently protected open space.
However, some residents said they're concerned the habitat will never return to the way it was.
"It can't be remediated. It's one of those things that once it's gone, it's extinct," said LeCompte. "It can't be just replicated overnight by filling in some dirt and then replanting things."
The city said the concrete flood wall running parallel to Highway 36 will stand between 6 and 18 feet tall. The entire CU South site will be closed during construction.
