Mckinley Lake Reservoir Report

Last Updated: December 5, 2025

Mckinley Lake, located in Missoula, Montana, is a picturesque earth dam structure completed in 1923 for water supply purposes.


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Summary

With a height of 7 feet and a length of 364 feet, the dam boasts a storage capacity of 168 acre-feet and serves as a vital water resource for the local community. The lake covers a surface area of 15 acres and is fed by the TR-LAKE CREEK, with a drainage area of 0.29 square miles.

Despite its age, Mckinley Lake remains a well-regulated and inspected dam, with the Montana Department of Natural Resources and Conservation overseeing its permitting, inspection, and enforcement. The dam's spillway, with a width of 10 feet, is uncontrolled, and the outlet gates are also uncontrolled. The hazard potential of the dam is considered significant, with a moderate risk assessment rating of 3. While the condition assessment is currently not rated, the dam's risk management measures and emergency action plan are in place to ensure the safety of the surrounding area in the event of an emergency.

In the beautiful setting of Missoula, Mckinley Lake stands as both a functional water supply source and a potential hazard to be managed carefully. With its historical significance and important role in the community's water management, the dam serves as a reminder of the importance of maintaining and regulating water resources in the face of changing climate conditions.

Year Completed

1923

Dam Length

364

Dam Height

7

River Or Stream

TR-LAKE CREEK

Primary Dam Type

Earth

Surface Area

15

Hydraulic Height

3

Drainage Area

0.29

Nid Storage

168

Structural Height

7

Outlet Gates

Uncontrolled

Hazard Potential

Significant

Nid Height

7
       
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.