DENVER - Two joint exercises simulating potentially catastrophic flood events affecting the Denver metropolitan area were held Feb. 26-27, 2025, at the Mile High Flood District headquarters in Denver, Colorado.
The exercises, planned and hosted by the U.S. Army Corps of Engineers, Omaha District’s Dam and Levee Safety Branch and Readiness Branch, brought together local, state and federal emergency managers along with local area law enforcement and principal information officers, to meet critical goals in emergency preparedness and response.
“Rehearsing agencies’ responses to exercise scenarios confirms or challenges preparedness plans and identifies improvement opportunities before a real flood or dam emergency,” said Amy Echols, a dam and flood risk communicator with the Omaha District. “These particular exercises helped ensure the practical understanding of roles and responsibilities across emergency level determinations, notifications and responses that would help protect the densely populated communities downstream of the three Omaha District dams in the area, and further down the South Platte River through downtown Denver.”
Briefings by the USACE team preceded the exercises on topics including the dam safety program, dam operations under normal conditions and during a flood event, and emergency action plans. The staff emphasized dams do not eliminate flooding, and many agencies, as well as the public, have roles in reducing flood impacts.
Both exercises, the first focusing on Cherry Creek Dam and Reservoir and the second focusing on Chatfield and Bear Creek dams and reservoirs, presented developing dam safety and flood scenarios. Each began with heavy rain in combination with an unseasonably warm weather melt of record snowpack that caused rapid runoff into the three reservoirs, resulting in historic water levels.
The simulated, progressive scenarios introduced both structural and operational issues at each dam and their related spillways, none of which has been tested to-date under flood flows. The scenarios and several timed injects built up scenes for the district’s own Tri-Lakes Project staff to determine appropriate actions for dam surveillance and operations under strained conditions.
Weather forecasts, evolving hydrologic conditions and other simulated circumstances pressed partner agencies to assess their evacuation procedures, responses to public reaction, and to anticipate significant critical infrastructure and population impacts that could occur in a flood emergency.
“The purpose of the tabletop exercise was to stress the participants with a plausible scenario to determine preparedness,” said Omaha District Civil Engineer Katie Seefus who manages water storage and releases for the Tri-Lakes Projects and who also helped develop the scenarios. “Extreme flood preparedness and response planning and practice is an incredibly important life-safety tool. It builds and maintains critical relationships, tests the effectiveness of the local, state and federal emergency action plans, and allows a better understanding of each agency’s role and what agencies can offer each other to help ensure effective responses to an emergency.”
There are more than 92,000 dams across the United States. The Omaha District owns and operates 28 dams throughout the Upper Missouri River Basin. The Tri-Lakes Project dams include Cherry Creek, Chatfield and Bear Creek dams, and are located to the west, south and southeast of Denver. As a system, these dams reduce flood risk for 2.8 million people in the greater Denver metropolitan area.
To learn more about dam and levee safety, visit: https://www.nwo.usace.army.mil/Missions/Civil-Works/Dam-and-Levee-Safety/. Visit the National Inventory of Dams at https://nid.sec.usace.army.mil/#/ for additional information such as flood inundation maps for communities downstream of dams.