Moyie Reservoir Report

Last Updated: December 20, 2025

Moyie is a gravity dam nestled along the scenic Moyie River in Boundary, Idaho.


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Summary

Built in 1949 by designer C. F. Griggs, this hydroelectric structure stands at an impressive height of 92 feet, with a dam length of 376 feet and a storage capacity of 540 acre-feet. The dam serves a critical purpose in harnessing the power of the river for hydroelectric generation, with a maximum discharge capacity of 21,000 cubic feet per second.

Managed by the Federal Energy Regulatory Commission, Moyie Dam is regulated and inspected to ensure its structural integrity and operational efficiency. With a spillway width of 96 feet and two slide gates for outlet control, the dam has a high hazard potential but a moderate risk assessment rating. Although the condition assessment is not available, the dam's emergency action plan is regularly updated and meets guidelines, ensuring prompt response to any potential risks or incidents.

Located just 8 miles from Bonners Ferry, Moyie Dam stands as a testament to sustainable energy generation and water resource management in the picturesque Idaho landscape. It serves as a vital infrastructure for both local government and environmental enthusiasts, showcasing the harmonious blend of technology and nature in the realm of water resources and climate preservation.

Year Completed

1949

Dam Length

376

Dam Height

62

River Or Stream

Moyie River

Primary Dam Type

Gravity

Surface Area

45

Hydraulic Height

68

Drainage Area

755

Nid Storage

540

Structural Height

92

Outlet Gates

Slide (sluice gate) - 2

Hazard Potential

High

Foundations

Rock

Nid Height

92
       
Seasonal Comparison

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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.