Dionysia Reservoir Report

Last Updated: December 5, 2025

Dionysia, located in Chouteau, Montana, is a privately owned earth dam completed in 1945 with a primary purpose of fire protection, stock, or small fish pond.


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Summary

This dam, situated on Dry Fork Coulee, stands at a height of 20 feet and has a storage capacity of 51 acre-feet. With a low hazard potential and a condition assessment of "Not Rated," Dionysia serves as a crucial infrastructure for water resource management in the region.

Managed by the Montana Department of Natural Resources and Conservation (DNRC), Dionysia is regulated and inspected by the state to ensure its safety and functionality. The dam, with a maximum storage capacity of 51 acre-feet, plays a vital role in fire protection and supporting livestock in the area. Despite being classified as a low hazard potential structure, Dionysia is essential for maintaining water resources and mitigating potential risks in the region.

Owned by a private entity, Dionysia serves as a key water management infrastructure in Montana, offering essential benefits for fire protection and livestock support. With its location in Virgelle and a close proximity to Congressional District 00, this earth dam plays a significant role in water resource management and climate resilience efforts in the region.

Year Completed

1945

Dam Length

500

Dam Height

20

River Or Stream

DRY FORK COULEE

Primary Dam Type

Earth

Hydraulic Height

20

Nid Storage

51

Hazard Potential

Low

Nid Height

20
       
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.