G N R R Dunkirk Reservoir Reservoir Report

Last Updated: April 26, 2026

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The G N R R Dunkirk Reservoir, located in Toole, Montana, is a private water supply reservoir built in 1889 on Dunkirk Coulee.


Summary

With a dam height of 14 feet and a storage capacity of 969 acre-feet, this reservoir serves as a crucial water resource for the surrounding area. The primary purpose of the reservoir is water supply, and it is regulated by the Montana Department of Natural Resources and Conservation (DNRC).

Despite being over a century old, the Dunkirk Reservoir continues to play a significant role in water management in the region. With a hazard potential rated as significant, the reservoir requires ongoing inspections and maintenance to ensure its structural integrity. The reservoir's condition is currently not rated, highlighting the need for a comprehensive assessment to address any potential risks and ensure the safety of the surrounding community.

As climate change impacts water resources, the Dunkirk Reservoir remains a vital asset for water supply in Toole County. With its historical significance and essential role in water management, the reservoir serves as a reminder of the importance of sustainable water resource management in the face of a changing climate.

15-Day Long Term Forecast


Dam Height

14

Hydraulic Height

14

Year Completed

1889

Nid Storage

969

River Or Stream

DUNKIRK COULEE

Dam Length

549

Hazard Potential

Significant

Primary Dam Type

Earth

Nid Height

14
       
Seasonal Comparison

5-Day Hourly Forecast Detail

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.
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