R-Janssen #1 Reservoir Report

Last Updated: December 6, 2025

R-Janssen #1 is a private earth dam located in Powder River, Montana, specifically in the city of MIZPAH along HAY CREEK.


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Summary

Completed in 1953, this dam serves multiple purposes including fire protection, stock, and small fish pond. With a height of 24 feet and a length of 360 feet, R-Janssen #1 has a storage capacity of 137 acre-feet and a normal storage level of 79 acre-feet.

Managed by the Montana Department of Natural Resources and Conservation (DNRC), R-Janssen #1 is classified as having a low hazard potential and is currently rated as "Not Rated" in terms of its condition assessment. The dam has not been inspected recently, and there are no emergency action plans (EAP) in place. Despite its lack of recent assessments and emergency preparedness measures, this dam continues to play a crucial role in providing water resources for fire protection and livestock in the surrounding area.

As a critical infrastructure for water management in the region, R-Janssen #1 underscores the importance of regular inspections, maintenance, and emergency preparedness to ensure the safety and reliability of the dam. Water resource and climate enthusiasts should monitor updates on the condition assessment, emergency action plans, and risk management measures for R-Janssen #1 to safeguard its functionality and mitigate potential risks to the community and environment.

Year Completed

1953

Dam Length

360

Dam Height

24

River Or Stream

HAY CREEK

Primary Dam Type

Earth

Hydraulic Height

24

Nid Storage

137

Hazard Potential

Low

Nid Height

24
       
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.