Lemm Dam Reservoir Report
Nearby: Little Pond Limpert No. 2
Last Updated: December 6, 2025
Lemm Dam, located in Harding, South Dakota, is a privately owned earth dam with a height of 20 feet and a length of 180 feet.
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Summary
Completed in 1949, the dam has a storage capacity of 60 acre-feet and serves the primary purpose of water resource management along the TR-Moreau River. Despite its age, the dam is rated as having a low hazard potential and is currently not rated for condition assessment.
Managed by the South Dakota Department of Environment and Natural Resources (DENR), Lemm Dam is subject to state regulation, inspection, and enforcement to ensure its safe operation. The dam is equipped with outlets but does not have a spillway, and its maximum discharge capacity is 945 cubic feet per second. While the dam has not been modified in recent years and lacks an emergency action plan, it remains an essential infrastructure for water supply and climate resilience in the region. For water resource and climate enthusiasts, Lemm Dam provides an intriguing case study of a historic earth dam still in operation today.
Year Completed |
1949 |
Dam Length |
180 |
Dam Height |
20 |
River Or Stream |
TR-MOREAU RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
20 |
Nid Storage |
60 |
Hazard Potential |
Low |
Nid Height |
20 |
Seasonal Comparison
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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.
Lemm Dam