There is a significant safety concern at Cherry Creek Dam because of its location in a densely populated area that includes much of downtown Denver, and the dam’s potential for overtopping during an extreme rain event. Although the chances of overtopping or failure are very remote, the consequences, which include life loss, economic loss, and environmental damage, are what designate Cherry Creek as a high risk dam.
Under maximum conceivable flooding conditions, Cherry Creek Dam has the potential for overtopping and failure. The Water Control and Water Quality Section of the Hydrologic Engineering Branch in the USACE, Omaha District is studying potential modifications to the water control plan for Cherry Creek Dam. The goal of the study is to establish a timeline for increased releases from Cherry Creek Dam in an extreme flooding event to reduce the potential for overtopping and failure as well as the overall flood extent.
Cherry Creek Dam is managed in combination with Chatfield and Bear Creek Dams to mitigate flood risk in the Denver area. The current water control plan for Cherry Creek Dam limits releases from the outlet structure to not exceed a flow rate of 5,000 cfs at the Denver stream gage. The targeted flow at this stream gage includes the uncontrolled drainage flooding in Denver, Colorado, reservoir releases from Cherry Creek, Chatfield and Bear Creek Dams, and is imposed to prevent significant flooding in downtown Denver.
The following will be considered in the study: (1) removing the 5,000 cfs Denver maximum flow target to ensure releases can be made from Cherry Creek, (2) increasing Cherry Creek Dam releases above the 5,000 cfs limit (up to 13,300 cfs), and (3) evaluating added impacts of Cherry Creek Dam releases to existing uncontrolled drainage flooding.
Releasing more water from Cherry Creek Dam during extreme flooding would significantly reduce the cost of structural modifications to prevent overtopping and could prevent dam overtopping during some extreme events. Results from this study will be incorporated into the Cherry Creek Dam Safety Modification Study.