Fort Peck in Valley County, Montana — The American West (Mountains)
Diverting the Mighty Missouri
Around Fort Peck Dam
Photographed by Barry Swackhamer, August 26, 2020
1. Diverting the Mighty Missouri Marker
Captions: (middle left) Intake structure of the diversion tunnels nearing completion on June 30, 1936. Today the intake structure is located in the Fort Peck Reservoir below 200 feet of water.; (center) Workers pose for a photo immediately after they finished pouring concrete in the tunnel. The steel liner and bulkheads behind the workers hold the concert in place. February 3, 1937.; (bottom center) Once the dike was blasted on June 24, 1937, the Missouri River ran through the diversion funnels.; (middle right) Tunnel outlets on the downstream side of the dam under construction in September, 1935. Each tunnel is more than one mile long with a diameter of more than 24 feet.
Four underground tunnels were built to move water around the dam, from Fort Peck Reservoir to the Missouri downstream
On June 24, 1937, the dike holding back the Missouri River was blasted with dynamite. Since then, the river has flown through these tunnels. The only other way water can be released from the reservoir is when the lake becomes high enough to discharge water through the spillway.
About 4,000 men worked day and night for nearly four years to build the tunnels. The tunnels required 117 million pounds of steel, 660,000 cubic yards of concrete, and the removal of nearly 4 million cubic yards of material-enough to fill 500,000 dump trucks.
Each tunnel was designed to safely carry the entire flow of the Missouri River on its own. Today, two of the tunnels feed water to the powerhouses, while the other two are reserved for bypass flows if needed.
Erected by U.S. Army Corps of Engineers.
Topics. This historical marker is listed in these topic lists: Charity & Public Work • Waterways & Vessels. A significant historical date for this entry is June 24, 1937.
Location. 48° 0.604′ N, 106° 25.276′ W. Marker is
this page online
Regionally, this marker is in Montana’s Missouri River Country. It is also in the American Mountain West, in the Lewis & Clark Corridor, on the prairies, on the Great Plains, and specifically on the Northern Plains. Globally, it is in North America, the Western Hemisphere, the Western World, and the Anglosphere. Historically, it finds itself in what was once Ruperts Land and also the Louisiana Purchase.
Other nearby markers. At least 8 other markers are within walking distance of this marker: Powerful Afterthoughts (here, next to this marker); Town Built for a Dam (a few steps from this marker); Boomtowns on the Outskirts (a few steps from this marker); Dredging Up The Earth To Build A Dam (about 300 feet away, measured in a direct line); In Memory (approx. one mile away); Built with Muscle and Muck
Photographed by Barry Swackhamer, August 26, 2020
2. Diverting the Mighty Missouri Marker
Credits. This page was last revised on July 26, 2026. It was originally submitted on December 7, 2020, by Barry Swackhamer of Brentwood, California. This page has been viewed 281 times since then and 32 times this year. Photos: 1, 2. submitted on December 7, 2020, by Barry Swackhamer of Brentwood, California.
