Sun Coulee Reservoir Report
Nearby: Big Timber #37 Big Timber #21
Last Updated: December 6, 2025
Sun Coulee, located in Rosebud County, Montana, is a privately owned earth dam completed in 1956 for fire protection, stock, and small fish pond purposes.
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Summary
With a height of 27 feet and a storage capacity of 476 acre-feet, this dam on the Sun Coulee river serves as a vital resource for the local community in Forsyth. The dam's low hazard potential and "Not Rated" condition assessment highlight its importance in ensuring water security and environmental sustainability in the region.
Managed by the DNRC and subject to state regulations, Sun Coulee plays a crucial role in maintaining water supply for irrigation, livestock, and emergency firefighting. Despite not having a designated spillway type or outlet gates, the dam's construction and operation are overseen by the state agency, emphasizing the commitment to safety and compliance with regulatory standards. The dam's location in a congressional district represented by Greg Gianforte underscores its significance in safeguarding water resources and enhancing resilience to climate impacts.
As an integral part of the water infrastructure in Montana, Sun Coulee stands as a testament to effective water management practices and the importance of maintaining and inspecting dams for long-term sustainability. With its strategic location and purpose-driven design, this earth dam serves as a vital asset for water resource and climate enthusiasts, demonstrating the intersection of human needs and environmental stewardship in ensuring a secure water supply for future generations.
Year Completed |
1956 |
Dam Length |
1000 |
Dam Height |
27 |
River Or Stream |
SUN COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
24 |
Nid Storage |
476 |
Hazard Potential |
Low |
Nid Height |
27 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Sun Coulee