Johnson #1 Reservoir Report
Nearby: T L Johnson #5 Harstad #1
Last Updated: December 7, 2025
Johnson #1 is a private water resource located in Rosebud County, Montana, specifically in the city of Forsyth.
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Summary
Built in 1955 and designed by the USDA NRCS, this earth dam serves multiple purposes such as fire protection, stock, and small fish pond. With a dam height of 20 feet and a storage capacity of 155 acre-feet, Johnson #1 plays a crucial role in the local ecosystem by providing water for various uses.
Managed by the DNRC, Johnson #1 is considered to have low hazard potential and a moderate risk level. The dam has a spillway width of 75 feet and a maximum discharge of 700 cubic feet per second, ensuring proper water flow management during extreme weather events. Despite being in good condition and not having a current risk assessment, Johnson #1 remains an essential infrastructure for maintaining water resources and aiding in climate control efforts in the area.
With a location on Living Ash Creek, Johnson #1 is a key component in the water infrastructure of the region, contributing to the overall water management efforts in Montana. Its construction and design by the Natural Resources Conservation Service highlight the importance of sustainable water resource development and the need for effective dam maintenance to ensure the safety and functionality of such vital structures in the face of changing climate conditions.
Year Completed |
1955 |
Dam Length |
500 |
Dam Height |
20 |
River Or Stream |
LIVING ASH CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
20 |
Nid Storage |
155 |
Hazard Potential |
Low |
Nid Height |
20 |
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.
Johnson #1