Dam Design and Construction

NorthWestern Energy preparing to upgrade Black Eagle Dam spillway

NorthWestern Energy preparing to upgrade Black Eagle Dam spillway

NorthWestern Energy is launching a major project to upgrade the spillway of Black Eagle Dam on the Missouri River, enhancing the safety and reliability of the hydroelectric facility.

Black Eagle Dam impounds water for a 21 MW powerhouse in Montana. It is part of the Missouri-Madison Hydro Project, which consists of two dams (Hebgen and Madison) on the Madison River and seven dams (Hauser, Holter, Black Eagle, Rainbow, Cochrane, Rainbow and Morony) on the Missouri River. NorthWestern is authorized to operate all nine facilities by the Project 2188 license issued by The Federal Energy Regulatory Commission.

The upgrade project will involve installing new support structures and components of the spillway. The upgrade will improve the integrity of the dam and eliminate the need for manual ice removal, which is performed by NorthWestern Energy hydro crews during frigid temperatures. This will improve the safety of the workers and the efficiency of the operation.

The spillway upgrade will begin in September 2024 and take two years to complete. During this time, a barge will be located upstream of Black Eagle Dam to transport materials and equipment for the project.

NorthWestern Energy provides electricity and/or natural gas to about 775,300 customers in Montana, South Dakota, Nebraska and Yellowstone National Park. Nearly 36% of the electricity for its Montana customers comes from 100% clean hydroelectricity.