Marlo Johnson Reservoir Report
Nearby: Morris Jensen Jenson Dam
Last Updated: December 6, 2025
Marlo Johnson is a privately owned dam located in Perkins, South Dakota, along the TR South Grand River.
°F
°F
mph
Wind
%
Humidity
Summary
Constructed in 1959, this earth dam stands at a height of 31 feet and has a storage capacity of 112 acre-feet. With a low hazard potential and a condition assessment of "Not Rated," Marlo Johnson serves as a vital infrastructure for water resource management in the region.
Managed by the South Dakota Department of Environment and Natural Resources (DENR), Marlo Johnson is regulated, permitted, inspected, and enforced by the state authorities. The dam's primary purpose and associated structures are not specified in the data, but its significance in controlling water flow and providing storage for the surrounding area are evident. The dam's location within the St. Paul District of the US Army Corps of Engineers adds to its importance in water resource management.
Despite its low hazard potential, Marlo Johnson plays a crucial role in mitigating flood risks and regulating water discharge in the region. With its state-regulated status and compliance with inspection and enforcement measures, this earth dam stands as a testament to effective water resource management and climate resilience efforts in South Dakota.
Year Completed |
1959 |
Dam Length |
380 |
Dam Height |
31 |
River Or Stream |
TR SOUTH GRAND RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
31 |
Nid Storage |
112 |
Hazard Potential |
Low |
Nid Height |
31 |
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.
Marlo Johnson