Petranek Reservoir Reservoir Report
Nearby: Petranek Taylor Fish (Fergus)
Last Updated: December 5, 2025
Petranek Reservoir, located in Fergus County, Montana, is a private earth dam constructed in 1937 by the USDA NRCS for fire protection, stock, and as a small fish pond.
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Summary
The reservoir has a dam height of 34 feet and a storage capacity of 125 acre-feet, providing a reliable water source for agricultural and wildlife needs in the area. Situated on TR-ARMELLS CREEK, Petranek Reservoir plays a crucial role in maintaining water supply security in the region.
Despite being privately owned, Petranek Reservoir is state-regulated by the Montana Department of Natural Resources and Conservation (DNRC), ensuring that it meets necessary safety and operational standards. With a low hazard potential and a condition assessment of "Not Rated," the reservoir poses minimal risks to the surrounding community. While the dam has not been modified in recent years, regular inspections and enforcement by state agencies guarantee its structural integrity and functionality for the future.
In the event of an emergency, the reservoir is equipped with an Emergency Action Plan (EAP) to guide response efforts and ensure public safety. Although the details of the EAP and risk assessment are not currently available, Petranek Reservoir remains a vital resource for water management and climate resilience in the region, serving as a model for sustainable water infrastructure development.
Year Completed |
1937 |
Dam Length |
584 |
Dam Height |
34 |
River Or Stream |
TR-ARMELLS CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
30 |
Nid Storage |
125 |
Hazard Potential |
Low |
Nid Height |
34 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Missouri River Near Landusky Mt
|
9100cfs |
Judith River Nr Mouth
|
368cfs |
Peoples Creek Near Hays Mt
|
4cfs |
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.
Petranek Reservoir