Mogen #1 Reservoir Report
Nearby: Lee #6 Montana #7
Last Updated: December 7, 2025
Mogen #1 is a privately owned earth dam located in Rosebud, Montana, along the TR-Yellowstone River.
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Summary
Designed by the USDA NRCS and completed in 1970, this dam serves multiple purposes, including fire protection, stock watering, and small fish pond support. With a height of 15 feet and a length of 100 feet, Mogen #1 has a storage capacity of 56 acre-feet and a drainage area of 0.94 square miles.
Despite being classified as having a low hazard potential, Mogen #1 is regulated and inspected by the Montana Department of Natural Resources and Conservation (DNRC) to ensure its safety and compliance with state regulations. The dam has an uncontrolled spillway with a width of 20 feet and is situated in Congressional District 00, Montana, represented by Greg Gianforte (R). While the dam's condition assessment is not rated, its risk assessment is moderate.
Water resource and climate enthusiasts will appreciate Mogen #1 as a vital infrastructure providing water storage and supply for various purposes in the Rosebud area. This dam, with its historical significance and environmental impact, contributes to the overall water management strategies in Montana. Its location along the Yellowstone River highlights its importance in supporting local ecosystems and agricultural activities, making it a valuable asset in water resource conservation and management efforts.
Year Completed |
1970 |
Dam Length |
100 |
Dam Height |
15 |
River Or Stream |
TR-YELLOWSTONE RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
15 |
Drainage Area |
0.94 |
Nid Storage |
56 |
Hazard Potential |
Low |
Nid Height |
15 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Mogen #1