LONGMONT, Colo. – The U.S. Army Corps of Engineers, Omaha District, awarded a contract in January 2025 to begin construction on a major flood risk reduction project in Longmont, Colorado, aimed at better protecting the city from potential flooding along St. Vrain Creek.

Longmont was one of the most affected communities during the catastrophic flood event in September 2013, with large amounts of flood water attributed to the creek.

Upwards of five feet of water flowed through residential properties, including multi-family housing on the south side of the river along with industrial properties on the north side. Damage to public infrastructure exceeded $148 million.

“The U.S. Army Corps of Engineers has been partnering with the City of Longmont to assist with their vision for recovering from the catastrophic 2013 flood while providing increased flood resiliency along the St. Vrain Creek corridor,” said Greg Johnson, Omaha District plan formulation section chief. “This project contributes to that vision by addressing one of the highest risk reaches of the stream resulting in reducing flood risks and strengthening protections for the city and surrounding communities."

The approved project will include critical channel improvements, the construction of a left bank levee adjacent to Izaak Walton Pond, a grade transition structure, and the replacement of the aging Boston Avenue Bridge.

The new Boston Avenue Bridge will be longer and the channel underneath the bridge will be wider and deeper, resulting in a structure that is better able to withstand larger flood events such as 100-year flood flows. The City of Longmont took on the design and construction of the bridge replacement portion of the project as an in-kind effort toward the project cost-share. The bridge replacement work is well underway by the local contractor.

There also will be several multi-modal improvements made while the bridge is being replaced. The surface sidewalks will be widened, the bike lanes will be redesigned to meet current standards, and the pedestrian underpass will be upgraded so there is less likelihood of having to close the underpass due to flooding.

A grade transition structure is being designed to help control water flow and reduce the risk of flooding by gradually transitioning between different elevations, which helps prevent erosion and enhances the stability of flood control systems.

 “The federal project is a keystone element of the city’s overarching flood risk reduction efforts. Improving the channel capacity in this reach keeps the floodwaters from breaking out of the creek channel through Izaak Walton Pond and into downtown Longmont,” said Jen Gitt, Omaha District project manager.

The project is part of the city’s Resilient St. Vrain Project (RSVP) which is a multi-year, multi-phase flood recovery project to restore the St. Vrain Greenway and protect people and property from future flood risks.

The City of Longmont plans to continue flood risk reduction work along the channel upstream of the federal project once construction is complete.

The St. Vrain Creek extends north and west of the City of Longmont in Boulder County. This area is highly urbanized with residential, commercial and industrial land uses, and development has both restricted and influenced the alignment of St. Vrain Creek.

This significant undertaking is expected to enhance the safety and resilience of the community, reducing flood risks and improving infrastructure in the area.

LONGMONT, Colo. – A U.S. Army Corps of Engineers, Omaha District flood risk reduction project along the St. Vrain Creek in Longmont, Colorado, is substantially complete, marking another milestone in the community’s ongoing effort to improve flood resilience following the catastrophic flooding of 2013.

The federally funded project is a cost-shared Section 205 Flood Risk Management Project, with the City of Longmont serving as the non-federal sponsor.

“Communities across the country face the challenge of balancing flood risk, infrastructure needs and natural resource stewardship,” said Col. Joe Sahl, Omaha District commander. “Projects like this demonstrate the value of bringing federal engineering expertise together with local knowledge to deliver solutions that protect communities.”

The federal project includes improvements designed to increase the creek’s ability to safely convey flood flows while reducing future flood risk. Major elements include widening and lowering the creek channel, replacing a bridge, constructing a grade transition structure and installing a drainage structure through an engineered earthen embankment between the creek and Izaak Walton Pond.

The project is one component of Longmont’s broader Resilient St. Vrain Project, which began following the September 2013 floods that caused extensive damage to homes, businesses, public spaces and infrastructure throughout the community.

The federal project extends from Boston Avenue upstream past Sunset Street and includes improvements through the Izaak Walton nature area. Once complete, the improvements will help reduce flood risk for portions of Longmont while contributing to the city’s broader flood resilience goals.

“This project is a great example of our commitment to working alongside a local partner to address a community’s flood risk,” said Jennier Gitt, who served as the district’s project manager on this effort. “Reaching substantial completion is a significant milestone, but it’s also one piece of Longmont’s much larger effort to build a more resilient St. Vrain Creek.”

The City of Longmont will continue its work on the remaining portions of the Resilient St. Vrain Project master plan, including a final reach upstream of the federal project area.

The Omaha District provides engineering and construction expertise for water resources projects across its nine-state area of responsibility, working with communities and other partners to reduce flood risk, restore ecosystems and improve the resilience of the nation’s infrastructure.