A Irion #1 Reservoir Report
Nearby: J Janssen #1 Spear #1
Last Updated: December 6, 2025
A Irion #1 is a privately-owned dam located in Powder River, Montana, along Mizpah Creek.
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Summary
Built in 1953, this earth dam stands at 12 feet tall and stretches 210 feet in length, providing essential functions for fire protection, stock, and small fish pond support. With a storage capacity of 79 acre-feet, the dam serves a critical role in the region's water resource management.
Managed by the Montana Department of Natural Resources and Conservation (DNRC), A Irion #1 is classified as a low hazard potential structure with a current condition assessment of "Not Rated." Despite lacking recent inspection data, the dam is regulated, permitted, and inspected by the state, ensuring its reliability and safety. With a primary purpose of safeguarding against fires and supporting local livestock and aquatic life, this dam showcases the importance of sustainable water infrastructure in mitigating climate-related risks.
While lacking detailed information on emergency preparedness and risk management measures, A Irion #1 remains an essential asset for water resource and climate enthusiasts to monitor. As part of the broader network of dams within the Omaha District, this structure contributes to the overall water management efforts in the region. With its historical significance and ongoing operational functions, A Irion #1 highlights the intersection of human development and environmental stewardship in balancing water resource needs with climate resilience.
Year Completed |
1953 |
Dam Length |
210 |
Dam Height |
12 |
River Or Stream |
MIZPAH CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
12 |
Nid Storage |
79 |
Hazard Potential |
Low |
Nid Height |
12 |
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.
A Irion #1