Black Eagle Reservoir Report

Last Updated: December 5, 2025

Black Eagle, a privately owned hydroelectric dam located on the Missouri River in Fort Benton, Montana, was completed in 1891 and stands at a height of 35 feet.


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Summary

With a primary purpose of generating hydroelectric power, the dam also serves recreational purposes, covering a surface area of 402 acres and holding a normal storage capacity of 1710 acre-feet. The dam boasts a controlled spillway with a width of 625 feet and a maximum discharge rate of 94,000 cubic feet per second, making it a crucial structure in managing water resources in the area.

Despite its age, Black Eagle remains a vital component of the local water infrastructure, with the Federal Energy Regulatory Commission overseeing its operations and inspections. The dam's hazard potential is classified as high, with a very high risk assessment score of 1, highlighting the importance of proper risk management measures. While the condition assessment of the dam is currently not available, regular inspections and emergency action plans are essential to ensure the safety and functionality of this historic gravity dam for both water resource management and energy production in the region.

Situated in the picturesque Cascade County, Black Eagle Dam stands as a testament to the intersection of water resource management, hydroelectric power generation, and recreational activities along the Missouri River. With its impressive structural height of 40.5 feet and long dam length of 1670 feet, the dam continues to play a significant role in the local community. As climate change poses challenges to water resources, the maintenance and monitoring of dams like Black Eagle are crucial for adapting to shifting environmental conditions and ensuring sustainable water management practices for future generations.

Year Completed

1891

Dam Length

1670

Dam Height

35

River Or Stream

Missouri River

Primary Dam Type

Gravity

Surface Area

402

Hydraulic Height

36

Drainage Area

22100

Nid Storage

1710

Structural Height

40.5

Outlet Gates

Other Controlled - 25, Slide (sluice gate) - 8

Hazard Potential

High

Nid Height

41
       
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Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.