Noxon Rapids

Noxon Rapids is a gravity dam located in Sanders County, Montana, built in 1960. It carries a High hazard potential classification and has a fair condition assessment.

About Noxon Rapids

The primary purpose of Noxon Rapids is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by Avista Corporation (private). It impounds the Clark Fork River near Noxon, Mt.

The dam stands 260 feet tall and stretches 5,840 feet across, creates a reservoir covering 7,940 acres, has a maximum storage capacity of 400,000 acre-feet, and collects water from a drainage area of 21,800 square miles. Completed in 1960, the structure is well into its service life at over 50 years old.

This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 07/26/2022.

At 260 feet, this dam is taller than 99% of all dams in the United States.

Living Downstream

If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Montana dam safety program can provide more specific information about emergency planning for this structure.

Search for dams near your address to see all dams in your area with hazard classifications and safety data.

High HazardFair ConditionEmergency Action Plan: Yes

Location

StateMontana
CountySanders
Nearest CityNoxon, Mt
River/StreamClark Fork River
Coordinates47.96166, -115.73344

Physical Characteristics

Dam TypeGravity
NID Height260 ft
Dam Height135 ft
Dam Length5,840 ft
Year Completed1960 (66 years old)

Storage & Hydraulics

NID Storage400,000 acre-ft
Max Storage400,000 acre-ft
Normal Storage400,000 acre-ft
Surface Area7,940 acres
Drainage Area21,800 sq mi
Max Discharge364,000 cfs
Spillway TypeControlled

Ownership & Safety

PurposeHydroelectric
OwnerAvista Corporation
Owner TypePrivate
Hazard ClassificationHigh
Condition AssessmentFair
Last Inspection07/26/2022
Emergency Action PlanYes

Identifiers

NID IDMT00223
Federal IDMT00223
More InfoState Dam Safety Program