Porcupine (Rosebud) Reservoir Report
Nearby: Standish #5 Standish #4
Last Updated: December 6, 2025
Porcupine (Rosebud) is a private earth dam located in Rosebud, Montana, designed by the USDA NRCS and completed in 1968.
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Summary
The dam serves multiple purposes including fire protection, stock, and small fish pond management. It stands at 28 feet tall with a length of 700 feet, providing a storage capacity of 101 acre-feet of water. Situated on TR-Rattlesnake Creek, the dam is regulated by the Montana Department of Natural Resources and Conservation (DNRC) and is inspected and enforced by state agencies.
The dam has a low hazard potential and is currently rated as "Not Rated" in terms of its condition assessment. Despite being uncontrolled, the spillway has a width of 100 feet to allow for proper water discharge. While the risk assessment for the dam is moderate, it meets guidelines for emergency action plans and risk management measures are in place. The area surrounding the dam is primarily used for agriculture, with a drainage area of 1.41 square miles and normal storage capacity of 63 acre-feet. Overall, Porcupine (Rosebud) dam plays a vital role in water resource management and climate resilience in the region.
Year Completed |
1968 |
Dam Length |
700 |
Dam Height |
28 |
River Or Stream |
TR-RATTLESNAKE CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
28 |
Drainage Area |
1.41 |
Nid Storage |
101 |
Hazard Potential |
Low |
Nid Height |
28 |
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.
Porcupine (Rosebud)