Cooper-Adams #4 Reservoir Report

Last Updated: December 5, 2025

Cooper-Adams #4 is a privately owned irrigation dam located in Fergus County, Montana, along Bear Creek.


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Summary

Completed in 1960, this earth dam stands at a height of 15 feet and has a storage capacity of 138 acre-feet. It serves the primary purpose of irrigation and is regulated by the Montana Department of Natural Resources and Conservation.

Despite being classified as having a low hazard potential, Cooper-Adams #4 has not been rated for its condition assessment. The dam has not undergone recent inspections, and no emergency action plan is in place. While the risk assessment and management measures for this structure have not been specified, it is essential for stakeholders to prioritize the safety and maintenance of this dam to ensure its continued functionality and prevent potential risks to the surrounding area.

Located in a picturesque setting in Mosby, Montana, Cooper-Adams #4 is a vital resource for irrigation purposes in the region. As water resource and climate enthusiasts, it is important to monitor and advocate for the proper maintenance and safety protocols for dams like Cooper-Adams #4 to protect both the environment and the communities that rely on them for water supply and agriculture.

Year Completed

1960

Dam Length

450

Dam Height

15

River Or Stream

BEAR CREEK

Primary Dam Type

Earth

Hydraulic Height

15

Nid Storage

138

Hazard Potential

Low

Nid Height

15
       
Seasonal Comparison

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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.