Helen B Reservoir Report
Nearby: Burch Lost Calf Detention Dam
Last Updated: December 5, 2025
Helen B is a private irrigation dam located in Carter County, Montana, near Marmarth, North Dakota.
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Summary
Built in 1966 by the USDA NRCS, this earth dam stands at a height of 81 feet and spans 300 feet in length. With a primary purpose of irrigation, Helen B has a storage capacity of 123 acre-feet and serves the Cow Creek watershed with a drainage area of 5 square miles.
Managed by the DNRC and regulated by the state of Montana, Helen B is categorized as having a low hazard potential and its condition assessment is currently marked as "Not Rated". Despite being inspected in 1968, there is no recent data available on its current condition. The dam has a spillway width of 80 feet and a maximum discharge capacity of 1025 cubic feet per second, ensuring the safety and efficiency of water flow during peak periods.
Located in a scenic and vital part of the region, Helen B plays a crucial role in supporting agricultural activities and water resource management in the area. Enthusiasts of water resources and climate will find this dam an interesting subject for study and exploration, given its historical significance and contribution to the local ecosystem.
Year Completed |
1966 |
Dam Length |
300 |
Dam Height |
81 |
River Or Stream |
TR-COW CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
18 |
Drainage Area |
5 |
Nid Storage |
123 |
Hazard Potential |
Low |
Nid Height |
81 |
Seasonal Comparison
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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.
Helen B