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Location: Fort Peck, MT - River mile 1771.5

Fort Peck Lake is 134 miles long, with over 1,500 miles of shoreline. The dam, just west of U.S. Interstate 2 and south of Glasgow, Montana, consists of an earthen embankment, outlet tunnels for releasing stored water, two powerhouses, and 16 gates on a concrete-lined spillway to the west of the dam. During normal operations, water is released through the powerhouse to generate power and balance reservoir levels for other uses. Water can also be released through the spillway gates as operations shift to reducing flood risks during periods of high runoff.

Fort Peck Dam and Fort Peck Lake provide many benefits to the local and regional public and to the nation. These include reducing the loss of life and property damage from floods, producing hydropower, and providing water intakes for municipal and industrial uses. The storage and release of water also benefits recreation, irrigation, water quality, fish and wildlife, and commercial navigation. USACE began construction of the first powerhouse in 1941 but it was not completed until 1951 due to shortages of supplies and materials during World War II. After USACE completed the second powerhouse in 1961, the dam produces an average 1.1 billion kilowatt hours a year, or enough power to supply a town of 100,000 people.

The public lands and waters of also provide a wide variety of recreational activities, such as fishing, boating, and camping. USACE and several partners (federal, tribal, state, county, and city) operate campgrounds, parks, and marinas on the lake.

Hydropower production at Fort Peck was approved by the Fort Peck Power Act in 1938. Started in 1941, construction on the first power house was not completed until 1951 due to shortages of supplies and materials during World War II.

A second power house was later added to tunnel #2. Construction on it began in 1958 and was completed in 1961. Today the two power houses average 1.1 billion kilowatt hours a year, or enough power to supply a town of 100,000 people.

The Omaha District has prepared a Hydropower Master Plan outlining the future requirements for sustaining our hydropower mission capability. A strategic master plan will guide future programming and funding for all hydropower sustainment, rehabilitation, and modernization requirements in a way that provides predictable funding and maximizes efficiencies to ensure the long-term resilience and reliability of this critical national infrastructure.

The vast size of Fort Peck Lake and its remoteness from major population centers provide a variety of high quality outdoor experiences. Popular activities include camping, boating, fishing, hunting, sight-seeing, picnicking, biking, hiking, photography, watching wildlife and just relaxing.

So many miles of pristine shoreline serve as a haven for those wishing to get away from the stresses of modern life. There are 27 recreation areas located around the reservoir. The areas near and around the dam offer paved roads, electricity, showers, and playgrounds while facilities around the rest of the lake are more primitive with gravel roads, picnic tables and vault toilets. Access roads to many of the remote areas may be impassable in inclement weather.

Additional information about nearby activities, camping, day use, and reservations are available here.

During normal operations, USACE releases up to 15,000 cubic feet of water per second (cfs) (one cubic foot of water is equal to 7.5 gallons). The two outlet tunnels can release an additional 45,000 cfs. The spillway was designed to additionally release up to 250,000 cfs.

For perspective, the largest release of water from Fort Peck Dam as a result of flooding was a combined 65,900 cfs from the powerhouse and spillway in 2011. It is important to understand that the dam is designed to release up to 310,000 cfs when necessary and that dams do not eliminate flood risk.

As part of its Dam Safety Program, Omaha District conducts detailed engineering analyses to ensure its dams are safe and that risks to the public, property, and the environment are minimized to the extent possible. Dam safety standards and practices are continually updated to improve the maintenance and operation of dams to ensure they can safely 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. Fort Peck 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 Missouri River. 

Omaha District completed several risk reduction actions at Fort Peck Dam after the flooding of 2011.  These include the installation of additional drains through the dam’s foundation and additional instrumentation to enhance foundation monitoring. Repairs also were made to the spillway to improve its resiliency during future flood events.

Visit the National Inventory of Dams to learn more about how dams work and Fort Peck Dam risk assessments.