Sumo Reservoir Report
Nearby: R.E. Braun Dyan
Last Updated: December 5, 2025
Sumo is a state-regulated water resource located in Chouteau, Montana, specifically in Box Elder.
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Summary
Built in 1934, this earth dam stands at 20 feet in height and spans 350 feet in length, providing vital fire protection, stock, and small fish pond purposes. It is under the jurisdiction of the Montana Department of Natural Resources and Conservation (DNRC) and is regularly inspected, permitted, and enforced by the state agency.
With a low hazard potential and a condition assessment of "Not Rated," Sumo serves as a reliable resource for the local community. The dam has a storage capacity of 92 acre-feet and a maximum storage of 92 acre-feet, with a normal storage level of 20 acre-feet. Despite its age, Sumo remains a functional and essential structure for managing water resources in the area. While it has not been modified in recent years, the dam continues to meet the necessary guidelines and regulations for efficient operation.
In the event of emergencies, the dam's Emergency Action Plan (EAP) status and preparedness are not currently rated or updated, but the risk management measures and potential risks associated with the structure are under constant evaluation. As a key component of water management in the region, Sumo plays a crucial role in ensuring water safety and resource availability for the surrounding community, making it a significant asset for water resource and climate enthusiasts to monitor and appreciate.
Year Completed |
1934 |
Dam Length |
350 |
Dam Height |
20 |
River Or Stream |
TR-SPRING COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
20 |
Nid Storage |
92 |
Hazard Potential |
Low |
Nid Height |
20 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Missouri River At Virgelle Mt
|
4290cfs |
Teton River At Loma Mt
|
30cfs |
Marias River Near Loma Mt
|
335cfs |
Missouri River At Fort Benton Mt
|
4720cfs |
Marias River Near Chester Mt
|
249cfs |
Big Sandy Creek Near Havre Mt
|
6cfs |
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.
Sumo
Marias River