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Chatfield Dam and Lake

Chatfield Dam and Lake was the second of the three dam and reservoir projects built by the U.S. Army Corps of Engineers to collectively lower the risks to the Denver region from flooding that inundated the region for centuries. When not operating the dam to reduce flood impacts, USACE releases water from this tri-lakes system for recreation, water quality, and to support fish and wildlife.

Tri-Lakes Information

Chatfield Reservoir, Storage Reallocation Project

The Record of Decision was signed by the Assistant Secretary of the Army, Jo-Ellen Darcy, on May 29, 2014, approving the Feasibility Report and Environmental Impact Statement for the Chatfield Reservoir, Storage Reallocation Project.  For information on the implementation of the Project, please visit the Chatfield Reservoir Mitigation Company website.

 

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Description

Location: Chatfield Dam consists of an earthen embankment, an outlet structure for releasing stored water, and a spillway over which excess water can flow during times of extreme runoff from rain and snowmelt. Chatfield Lake, the reservoir behind the dam, lies on the South Platte River at its confluence with Plum Creek, near the foothills of the Rocky Mountains about 25 miles southwest of downtown Denver. More detailed information about the project’s features are available here.

Chatfield Dam and Lake
Chatfield Dam was the second of three dams built to reduce flooding risks in the Denver area. Located southwest of Denver on the South Platte River, construction of the dam was begun in 1967 and was completed in 1975. The dam measures approximately 13,136 feet in length with a maximum height of 147 feet from the streambed to the top of the dam.
Chatfield Dam and Lake
Chatfield Lake lies on the South Platte River at its confluence with Plum Creek, near the foothills of the Rocky Mountains about 25 miles southwest of downtown Denver. The lake is 2 miles long and has an average depth of 47 feet. The lake drains an area of approximately 3,018 square miles. The 1,479-surface-acre lake has a storage capacity of 27,046 acre-feet.
Chatfield Dam and Lake
Chatfield dam and reservoir are owned and operated by the U.S. Army Corps of Engineers. The Corps leases 5,381 land and water acres to the State of Colorado Department of Natural Resources Division of Parks and Outdoor Recreation to operate Chatfield State Park.

Operating for many benefits

The U.S. Army Corps of Engineers operates the dam and reservoir to provide many benefits to the local and regional public, most importantly the reduction of the loss of life and property damage from floods. USACE leases 5,381 land and water acres to the State of Colorado Parks and Wildlife Division to operate Chatfield State Park. USACE also leases separate portions of project property to the Parks and Wildlife Division for fish production and rearing areas, and to the City and County of Denver, which in turn has a management agreement with Denver Botanic Gardens.

Recreation

Chatfield Lake lies on the South Platte River at its confluence with Plum Creek, near the foothills of the Rocky Mountains about 25 miles southwest of downtown Denver. The lake is 2 miles long and has an average depth of 47 feet. The lake drains an area of approximately 3,018 square miles. The 1,479-surface-acre lake has a storage capacity of 27,046 acre-feet.

Reducing Flood Risk

During normal operations, the outlet structure provides water to downstream users and releases are generally less than 500 cubic feet of water per second. One cubic foot of water, or cfs, is equal to 7.5 gallons.  As operations shift to reducing flood risks during periods of high runoff, the outlet structure is used to manage the reservoir elevations and can release up to 8,400 cfs. The spillway was designed to additionally pass up to 184,000 cfs. For perspective, the largest release of water from Chatfield Dam as a result of flooding was approximately 3,350 cfs from the outlet structure in 1995. It is important to understand that the dam is designed to release up to  192,400 cfs when necessary and that this dam-or any other dam-does not eliminate flood risk.

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 Maintaining the Dam

As part of its Dam Safety Program, Omaha District conducts detailed engineering analyses to ensure its dams reduce risks to the public, property, and the environment to the extent possible. Dam safety standards and practices are continually updated to improve the maintenance and operation of dams to ensure they can reliably serve their original purposes. In addition, dam safety engineers across federal and state agencies share information as they learn about the performance of flood risk reduction structures built over many decades. They now use more precise, modern technologies and apply up-to-date science to reduce flood risk more effectively. Chatfield Dam is operating as designed but in the unlikely case of uncontrolled reservoir releases, significant consequences could impact downstream populations, including numerous urban centers along the South Platte River. 

While USACE continually evaluates how to further reduce the risks associated with Chatfield Dam, several risk reduction measures were completed including repairs to key spillway features to improve performance and improvements to runoff forecast models in coordination with the National Weather Service to accelerate public warnings from local emergency management agencies.  Visit the National Inventory of Dams to learn more about how dams work and Chatfield Dam’s risk assessments.

Chatfield Pool Elevations

Graphic of Chatfield Reservoir Pool Elevations