Charlotts Webb Reservoir Report

Last Updated: December 5, 2025

Located in Cascade County, Montana, Charlotts Webb is a privately owned earth dam completed in 1960 for fire protection, stock, and small fish pond purposes.


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Summary

Situated along the Portage Coulee, this low hazard potential dam stands at 20 feet in height with a length of 325 feet, providing a storage capacity of 82 acre-feet. While the dam is state-regulated and inspected, its condition assessment is currently not rated.

With its primary purpose being fire protection, Charlotts Webb serves as a vital resource for water management in the area. Despite its low hazard potential, the dam plays a crucial role in safeguarding the surrounding community and ecosystem. As an Earth dam, it showcases the importance of sustainable infrastructure for water resource management and climate resilience. Enthusiasts of water resources and climate will find Charlotts Webb to be an intriguing example of how private ownership contributes to the conservation and management of water resources in Montana.

Year Completed

1960

Dam Length

325

Dam Height

20

River Or Stream

PORTAGE COULEE

Primary Dam Type

Earth

Hydraulic Height

20

Nid Storage

82

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.