Oleary Reservoir Report
Nearby: B. Oleary Oleary Ranch 2
Last Updated: December 12, 2025
Oleary is a private dam located in Dewey, South Dakota, along the TR MOREAU river.
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Summary
Built in 1945, this earth dam stands at a height of 15 feet and has a length of 600 feet, providing a storage capacity of 80 acre-feet. The dam is regulated by the South Dakota Department of Environment and Natural Resources (DENR), with state jurisdiction, permitting, inspection, and enforcement in place to ensure its safety and compliance.
Despite its low hazard potential, Oleary has not been rated for its condition assessment. Emergency action plans and risk management measures are yet to be fully developed for this dam. While the dam has not been modified over the years, it plays a crucial role in water resource management in the area, with a normal storage capacity of 32 acre-feet and a maximum discharge of 1800 cubic feet per second. With its location in a state-regulated area, Oleary serves as a significant structure for water control and conservation efforts in South Dakota.
As an essential infrastructure in the St. Paul District, Oleary contributes to maintaining water resources and climate resilience in Dewey, South Dakota. With its historical significance and functional capacity, this dam stands as a testament to the importance of regulated private structures in supporting sustainable water management practices. As water resource and climate enthusiasts, understanding the role of dams like Oleary is key to appreciating the intricate balance between human development and environmental conservation in our changing world.
Year Completed |
1945 |
Dam Length |
600 |
Dam Height |
15 |
River Or Stream |
TR MOREAU |
Primary Dam Type |
Earth |
Hydraulic Height |
15 |
Nid Storage |
80 |
Hazard Potential |
Low |
Nid Height |
15 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Moreau R Near Whitehorse Sd
|
35cfs |
Grand R At Little Eagle Sd
|
47cfs |
Oak Cr Near Wakpala Sd
|
10cfs |
Moreau R Near Faith Sd
|
14cfs |
Cedar Creek Nr Raleigh
|
20cfs |
Cannonball River Nr Raleigh
|
40cfs |
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.
Oleary