Lewandowski Dam Reservoir Report
Nearby: Brown's Valley Dam Piotter Dam
Last Updated: December 13, 2025
Lewandowski Dam, located on the TR.-LITTLE MINNESOTA RIVER in Roberts, South Dakota, is a privately owned structure designed by USDA NRCS and completed in 2006.
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Summary
This earth dam stands at a height of 29 feet, with a storage capacity of 33 acre-feet and a maximum discharge of 325 cubic feet per second. The dam serves a primary purpose of water resource management, with a low hazard potential and a moderate risk assessment rating.
Managed by the South Dakota Department of Environment and Natural Resources (DENR), Lewandowski Dam is regulated, permitted, inspected, and enforced by the state. The dam features an uncontrolled spillway with a width of 24 feet and does not have outlet gates. Despite being in good condition and not rated for condition assessment, the structure's risk management measures and emergency action plan status remain undisclosed. Its location within the Omaha District further underscores its importance in mitigating the impact of climate change on water resources in the region.
Overall, Lewandowski Dam plays a crucial role in water resource management and climate resilience efforts in South Dakota. As a vital structure along the TR.-LITTLE MINNESOTA RIVER, it stands as a testament to the collaboration between private owners, government agencies, and design entities in safeguarding the local community against potential water-related hazards. With its strategic placement and functional design, the dam serves as a valuable asset in regulating water flow, storing essential water resources, and maintaining the ecological balance of the surrounding area.
Year Completed |
2006 |
Dam Length |
160 |
Dam Height |
29 |
River Or Stream |
TR.-LITTLE MINNESOTA RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
29 |
Nid Storage |
33 |
Outlet Gates |
None |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
29 |
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.
Lewandowski Dam