Johnson Reservoir Report
Nearby: Tribe No.4 J. Reich No.1
Last Updated: December 7, 2025
Johnson is a private dam located in Ziebach, South Dakota, along the TR MOREAU river.
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Summary
Built in 1953, this Earth-type dam stands at 21 feet tall and spans 520 feet in length, with a storage capacity of 132 acre-feet. Managed by the Natural Resources Conservation Service, Johnson is regulated by the South Dakota Department of Environment and Natural Resources, ensuring regular inspections and enforcement of safety measures.
Despite its low hazard potential and "Not Rated" condition assessment, Johnson plays a crucial role in water resource management in the region. With a normal storage capacity of 80 acre-feet and a maximum discharge of 2100 cubic feet per second, this dam helps regulate water flow and provides essential irrigation and flood control benefits to the surrounding area. Dusty Johnson (R) serves as the representative for this district, overseeing any federal involvement related to Johnson.
Enthusiasts of water resources and climate will find Johnson to be an intriguing structure that balances the needs of agriculture and environmental protection. Its historical significance, combined with its ongoing regulatory oversight and operational functionality, make it a noteworthy example of how private dams contribute to sustainable water resource management in South Dakota.
Year Completed |
1953 |
Dam Length |
520 |
Dam Height |
21 |
River Or Stream |
TR MOREAU |
Primary Dam Type |
Earth |
Hydraulic Height |
21 |
Nid Storage |
132 |
Hazard Potential |
Low |
Nid Height |
21 |
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