Cochrane Reservoir Report

Last Updated: December 5, 2025

Cochrane is a private hydroelectric facility located on the Missouri River in Fort Benton, Montana.


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Summary

Built in 1957 by the Bechtel Corporation, this gravity dam stands at a height of 100 feet and has a structural height of 105 feet. With a normal storage capacity of 8,464 acre-feet and a maximum discharge of 140,000 cubic feet per second, Cochrane plays a crucial role in regulating water flow and generating hydroelectric power in the region.

Managed by the Federal Energy Regulatory Commission, Cochrane has a high hazard potential and is classified as a very high risk facility. With a spillway width of 280 feet and controlled spillway type, the dam is equipped with one other controlled outlet gate and seven Tainter (radial) gates. Despite its age, the condition assessment of Cochrane is not available, highlighting the need for regular inspections and maintenance to ensure the safety and efficiency of the structure.

As a key component of the water resource infrastructure in Montana, Cochrane serves as a reminder of the importance of proper management and maintenance of dams for both water supply and energy generation. With its strategic location on the Missouri River and significant storage capacity, Cochrane contributes to the overall water management efforts in the region, highlighting the interconnectedness of water resources and climate resilience.

Year Completed

1957

Dam Length

856

Dam Height

100

River Or Stream

Missouri River

Primary Dam Type

Gravity

Surface Area

249

Hydraulic Height

100

Drainage Area

23270

Nid Storage

8464

Structural Height

105

Outlet Gates

Other Controlled - 1, Tainter (radial) - 7

Hazard Potential

High

Nid Height

105
       
Seasonal Comparison

Weather Forecast

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.