O'Henry Reservoir Report
Nearby: South Sandstone Creek Dam R Maier
Last Updated: December 5, 2025
O'Henry is a private dam located in Ismay, Montana, along the TR-Pine Creek river.
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Summary
Completed in 1930, this earth dam is primarily used for fire protection, stock, and small fish pond purposes. With a height of 15 feet and a length of 660 feet, O'Henry has a storage capacity of 77 acre-feet, with a normal storage level of 40 acre-feet.
Managed by the Montana Department of Natural Resources and Conservation (DNRC), O'Henry has a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment. The dam is state-regulated and undergoes regular inspections, permitting, and enforcement to ensure its safety and compliance with regulations. Although there are no associated structures or emergency action plans in place, O'Henry serves as a vital resource for water management and conservation in the region.
For water resource and climate enthusiasts, O'Henry represents a historic and essential infrastructure for water storage and management in Fallon County, Montana. Its significance lies in providing water for fire protection, livestock, and recreational fishing, while also contributing to the overall ecological balance of the area. As a privately owned dam with state jurisdiction and oversight, O'Henry plays a crucial role in mitigating potential risks and ensuring the sustainable use of water resources for current and future generations.
Year Completed |
1930 |
Dam Length |
660 |
Dam Height |
15 |
River Or Stream |
TR-PINE CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
15 |
Nid Storage |
77 |
Hazard Potential |
Low |
Nid Height |
15 |
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.
O'Henry