North Fork Plug Dam Reservoir Report
Last Updated: December 20, 2025
North Fork Plug Dam, located in Valley County, Montana, along the Lone Tree Creek, is a Federal-owned gravity dam managed by the Bureau of Land Management.
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Summary
Standing at a structural height of 19 feet with a hydraulic height of 16 feet, the dam has a storage capacity of 122.96 acre-feet and covers a surface area of 73.06 acres. Although the dam's hazard potential is considered low, its condition assessment is currently marked as unsatisfactory, indicating a need for maintenance and potential improvements.
Despite its moderate risk assessment rating, North Fork Plug Dam has not undergone any significant modifications in recent years and lacks certain emergency preparedness measures, such as an Emergency Action Plan (EAP) and updated inundation maps. The dam's last inspection in September 2008 revealed its need for attention, highlighting the importance of regular monitoring and maintenance to ensure the safety and effectiveness of the structure. With its unique design incorporating buttress and stone core types, this dam serves as a key infrastructure for water resource management in the region and warrants ongoing attention to mitigate potential risks and ensure long-term functionality.
Dam Length |
4720 |
River Or Stream |
LONE TREE CREEK |
Primary Dam Type |
Gravity |
Surface Area |
73.06 |
Hydraulic Height |
16 |
Drainage Area |
0.3 |
Nid Storage |
122.96 |
Structural Height |
19 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
19 |
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.
North Fork Plug Dam