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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.

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.

Fort Peck Dam is the first dam built in the upper Missouri River Basin. The area surrounding Fort Peck was first charted by Lewis and Clark in 1804, and the pristine natural condition of the river and surrounding area awed the renowned explorers.

The Old Fort Peck trading post was built in 1867 on a narrow ledge of shale about 35 feet above the river, its rear wall abutting the hillside. The front of the stockade was so close to the ledge that it was an effective steamboat landing for sternwheelers that made frequent trips upstream. But the site of the old stockade was lost to the river near the turn of the century.

When President Franklin D. Roosevelt authorized the Fort Peck project in 1933, thousands of people from all over the country migrated to Montana during the midst of the Great Depression in hopes of earning a living. More than 7,000 men and women signed on to work on the dam in 1934 and 1935. Employment peaked at nearly 11,000 dam workers in 1936, and thousands more swarmed to Montana to set up businesses including food markets, hardware stores, butcher shops, general stores, saloons and brothels. More than eighteen boomtowns sprang up in the vicinity, and the "wild west" was reborn as a tiny and obscure township swelled from a population of a few hundred to nearly 40,000 people.

Maj. Clark C. Kittrell, who served as Corps of Engineers deputy district engineer at Fort Peck from 1933 to 1937 and as the district engineer from 1937 to 1940, defined the complexity of the mission: "No engineering job of this magnitude had ever been attempted with so short a time for planning."

New techniques had to be learned and developed as rapidly as ingenuity would allow. Countless technical problems arose and were solved. A shipyard, created on site, quickly turned out the "Fort Peck Navy," which would dredge the river bottom and pump the slurry that formed the dam. Workers overcame a massive slide in 1938, a year after closure was made, and with completion of the dam in sight. The last load of material was dumped in October 1940, almost seven years to the day after FDR’s authorization.

The legacy that is Fort Peck provides visitors a fascinating look into yesteryear. The town of Fort Peck, now an independent municipality, is a rare treasure. Neither progress nor modernization can erase the etchings of time that allow visitors a glimpse back at another era.

Many of the early buildings - some of which are listed on the National Register of Historic Building - still stand, symbols of a distant past, with an integrity that allows them to function yet today.