Noxon Rapids Reservoir Report

Last Updated: December 5, 2025

Noxon Rapids, a private hydroelectric dam located in Noxon, Montana, is a marvel of engineering designed by EBASCO and completed in 1960.


°F

°F

mph

Wind

%

Humidity

Summary

Standing at a height of 135 feet with a hydraulic height of 165.5 feet, this gravity dam spans 5,840 feet across the Clark Fork River. With a storage capacity of 400,000 acre-feet and a maximum discharge of 364,000 cubic feet per second, Noxon Rapids serves multiple purposes including hydroelectric power generation, fish and wildlife conservation, and recreational activities.

The dam's controlled spillway, with a width of 320 feet, helps manage water flow during periods of high inflow. Despite its hazard potential being rated as high, regular inspections by the Federal Energy Regulatory Commission ensure its structural integrity and safety. Noxon Rapids also boasts a surface area of 7,940 acres and drains an area of 21,800 acres, providing vital water resources for the region. As a significant player in the local ecosystem, the dam plays a crucial role in managing water levels and supporting wildlife habitats along the Clark Fork River.

For water resource and climate enthusiasts, Noxon Rapids represents a symbol of sustainable energy generation and environmental stewardship. Its very high risk assessment underscores the importance of effective risk management measures to safeguard the surrounding communities and ecosystems. With its impressive infrastructure and strategic location, Noxon Rapids stands as a testament to the intersection of human ingenuity and natural resource management in the dynamic landscape of Montana's waterways.

Year Completed

1960

Dam Length

5840

Dam Height

135

River Or Stream

Clark Fork River

Primary Dam Type

Gravity

Surface Area

7940

Hydraulic Height

165.5

Drainage Area

21800

Nid Storage

400000

Structural Height

260

Outlet Gates

Tainter (radial) - 8

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

260
       
Seasonal Comparison

Weather Forecast

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.