Ryan Reservoir Report

Last Updated: December 5, 2025

Ryan, also known as Volta, is a private hydroelectric dam located in Cascade, Montana, along the Missouri River.


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Summary

Built in 1915 by designer Charles T. Main, this gravity dam stands at a height of 61 feet and has a hydraulic height of 76 feet. With a structural height of 82 feet and a length of 1465 feet, Ryan boasts a storage capacity of 3653 acre-feet and a maximum discharge of 188,000 cubic feet per second.

Managed by the Federal Energy Regulatory Commission, Ryan serves as a vital source of energy production in the region. Despite its age, the dam's hazard potential is classified as high, with a very high risk assessment rating. While the condition assessment is not available, regular inspections are conducted to ensure the dam's safety and integrity. With a controlled spillway and multiple outlet gates, including slide gates, Ryan is equipped to handle emergency situations efficiently.

As a significant structure in the Omaha District, Ryan plays a crucial role in water resource management and climate adaptation efforts. Its historical significance and contribution to the region's energy needs make it a focal point for water resource and climate enthusiasts seeking to understand the intersection of infrastructure, sustainability, and environmental stewardship.

Year Completed

1915

Dam Length

1465

Dam Height

61

River Or Stream

Missouri River

Primary Dam Type

Gravity

Surface Area

168

Hydraulic Height

76

Drainage Area

23080

Nid Storage

3653

Structural Height

82

Outlet Gates

Other Controlled - 41, Slide (sluice gate) - 10

Hazard Potential

High

Nid Height

82
       
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.