Montana #19 Reservoir Report
Nearby: Thebes Lake Erickson L&L #5
Last Updated: December 6, 2025
Montana #19, also known as Sun Coulee Dam, is a state-owned structure located in Rosebud County, Montana.
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Summary
Built in 1956 by the USDA NRCS, this earth dam stands at a height of 20 feet and spans 750 feet in length. With a primary purpose of providing fire protection, stock, and a small fish pond, the dam has a storage capacity of 235 acre-feet and serves a drainage area of 3.13 square miles. It is regulated by the Montana Department of Natural Resources and Conservation (DNRC) and is subject to state permitting, inspection, and enforcement.
Despite its low hazard potential, Montana #19 presents a moderate risk level, rated at 3 on the risk assessment scale. The dam features an uncontrolled spillway with a width of 100 feet, capable of discharging up to 700 cubic feet per second. While the condition assessment is currently not rated, the dam has not undergone any modifications in recent years. Emergency action plans and inundation maps for the structure are yet to be prepared, highlighting the need for proactive risk management measures to ensure the safety and reliability of the dam in the face of potential climate challenges.
For water resource and climate enthusiasts, Montana #19 serves as a pivotal infrastructure for fire protection and agricultural purposes in the region. Its location in the Sun Coulee tributary and association with the Omaha District of the US Army Corps of Engineers underscores its importance in the local water management system. As the dam continues to support the community with its storage capacity and regulatory oversight by the DNRC, stakeholders must remain vigilant in monitoring and addressing any potential risks to ensure the long-term sustainability of this vital water resource asset.
Year Completed |
1956 |
Dam Length |
750 |
Dam Height |
20 |
River Or Stream |
TR-SUN COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
20 |
Drainage Area |
3.13 |
Nid Storage |
235 |
Hazard Potential |
Low |
Nid Height |
20 |
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.
Montana #19