Colorado State University students create, study miniature model of future dam for Fort Collins

CBS News

16-07-2025

Students at Colorado State University are now testing and studying a model of a dam that will one day be built northwest of Fort Collins. The Halligan Water Supply Project currently features a 116-year-old dam northwest of Fort Collins in the foothills. However, the aging dam not only needs to be replaced by also enlarged.
Replacing the existing dam not only will create a more reliable and safe structure for retaining water, but it will also allow the city to build a larger structure that will increase the amount of water the Halligan Reservoir can retain.
By increasing the reservoir's surface area from 253 acres to 391 acres, the city believes it can further expand its ability to provide reliable drinking water to residents.
Before construction of a new dam begins, students at CSU's hydraulics laboratory decided to help study how the future dam can best be designed.
In order to do so, they created a miniature model of the dam in a laboratory on the CSU Foothills Campus. They were provided scans and drawings of what the land just downstream of the dam will look like. That way, they could test how to best build a dam that would be able to complete controlled releases of water, while decreasing the likelihood of damage or injury to those downstream.
"This model is pretty much exact to what the actual reservoir is like with topography," said Catherine Lambert, a senior working on the project. "We started working on this project since last August."
The students used a combination of plexiglass, wood, foam and more to create a model of the landscape downstream from the proposed construction site.
"For every inch (on the model) that is two feet in real life," Lambert said.
Creating the near-exact replica of the topography was not a simplistic task.
"It took about three months to build," said Jeff Ellis, CSU's hydraulics lab manager.
"It is really cool seeing the models come to life, starting with a blank space and building up everything," Lambert said. "Starting with the floors, the frames and the bases. It is really fun seeing it come together. It is impressive and exciting."
The lab has a pump system that helps get thousands of gallons of water to flow over the dam and down into the model of the landscape.
The students are able to control the amount of water that comes over the dam as a way to better understand how the construction and landmass would respond to different levels of release and flooding.
The students are also studying where the best placement of a baffle box should be. Most dams feature a series of cement structures at their base, known as the baffle box, that help engineers further control waterflow.
"It is most important because that is what will calm the water down as it continues to flow," Lambert said.
The city acknowledges the project will help it secure more water for residents, allowing Fort Collins to have more reliable resources during years of drought.
"This is an important study because it effects Fort Collins," Lambert said.
Researchers believe the dam's design will be more than 60% complete by the end of 2025. It will need the approval of the U.S. Army Corps of Engineers before construction begins one day. It could be more than a decade before construction is completed.
"It is an important project because, on the Front Range, we don't have a lot of water. We need water storage," Ellis said. "With water storage comes large structure to hold back the water. With that, we need to optimize it with safety and cost."
Lambert said building the model and contributing to the design of the future construction is not only rewarding, but also helps him and fellow students expand their studies for future jobs.
"Doing the physical model, we are actually able to make changes in real time," Lambert said. "I am personally a visual learner. It is really nice being able to see what we are doing. It makes it easier to put our ideas into process."