Louis Lesmeister Reservoir Report
Last Updated: December 13, 2025
Louis Lesmeister is a privately owned dam located in Dewey, South Dakota, along the TR MOREAU river.
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Summary
Constructed in 1940, this earth dam stands at a height of 16 feet and has a length of 700 feet, providing a maximum storage capacity of 84 acre-feet. The dam is regulated by the South Dakota Department of Environment and Natural Resources (DENR) and undergoes regular inspections, with a low hazard potential rating.
Despite its age, Louis Lesmeister remains in good condition, with a "Not Rated" condition assessment. The dam has not been modified in recent years and does not have an emergency action plan (EAP) in place. While the risk management measures and inundation maps are not currently prepared, the dam's operations are overseen by the St. Paul District of the US Army Corps of Engineers.
For water resource and climate enthusiasts, Louis Lesmeister serves as a fascinating example of early 20th-century dam engineering in South Dakota. Its historical significance and ongoing regulatory oversight make it an interesting case study in the management of water resources and infrastructure in the region.
Year Completed |
1940 |
Dam Length |
700 |
Dam Height |
16 |
River Or Stream |
TR MOREAU |
Primary Dam Type |
Earth |
Hydraulic Height |
16 |
Nid Storage |
84 |
Hazard Potential |
Low |
Nid Height |
16 |
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 |
Cheyenne R Near Plainview Sd
|
0cfs |
Bad R Near Fort Pierre Sd
|
7cfs |
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.
Louis Lesmeister