Libby Dam Reservoir Report

Reservoir Report

Montana

Nearby: Kootenai Dvlpmnt Impoundment Dam Libbey's Label

Last Updated: December 24, 2025

Libby Dam, also known as Lake Koocanusa, is a Federal-owned structure located in Lincoln, Montana.

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Summary

Completed in 1973, this gravity dam serves multiple purposes including flood risk reduction, hydroelectric power generation, and recreation. With a height of 362 feet and a structural height of 422 feet, Libby Dam plays a crucial role in managing the flow of the Kootenai River and maintaining a maximum storage capacity of 6,027,000 acre-feet.

Despite being characterized with a high hazard potential, US Army Corps of Engineers (USACE) continuously implements risk management measures to ensure the safety of the dam and surrounding communities. USACE conducts regular inspections, maintains monitoring instruments, and collaborates with local emergency managers to update Emergency Action Plans and conduct emergency exercises. The dam's Emergency Action Plan is designed to mitigate potential risks, such as the unlikely scenario of a massive rockslide triggering a dam failure, which could result in deadly flooding downstream.

In the face of extreme weather events, such as heavy rainfall and snowmelt, USACE works diligently to balance flood risk by releasing water through the spillway to prevent overtopping and failure of the dam. While the risk assessment characterizes the dam's risk as moderate, USACE remains confident in the dam's structural integrity and its ability to reduce flood risks significantly. By employing proactive measures and closely monitoring conditions, USACE aims to minimize the potential for life loss and property damage, ensuring the continued effectiveness of Libby Dam in water resource management and climate resilience efforts.

Year Completed	1973
Dam Length	2890
River Or Stream	KOOTENAI RIVER
Primary Dam Type	Gravity
Surface Area	46500
Hydraulic Height	362
Drainage Area	8985
Nid Storage	6027000
Structural Height	422
Outlet Gates	Vertical Lift - 0
Hazard Potential	High
Nid Height	422

Explore Interactive Map

LIBBY DAM

Reservoir Report • Water Levels • Weather Forecast

December 24, 2025

Year_Completed	1973
Dam_Length	2890
River_Or_Stream	KOOTENAI RIVER
Primary_Dam_Type	Gravity
Surface_Area	46500
Hydraulic_Height	362
Drainage_Area	8985
Nid_Storage	6027000
Structural_Height	422
Outlet_Gates	Vertical Lift - 0
Hazard_Potential	High
Nid_Height	422

Seasonal Comparison

Weather Forecast

Nearby Streamflow Levels

Kootenai River Bl Libby Dam Nr Libby Mt 22100.0cfs	22100cfs
Fisher River Near Libby Mt 923.0cfs	923cfs
Yaak River Near Troy Mt 1540.0cfs	1540cfs
Tobacco River Near Eureka Mt 388cfs	388cfs
Kootenai River At Leonia Id 27600.0cfs	27600cfs
Clark Fork River Below Cabinet Gorge Dam Id 18300.0cfs	18300cfs

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.