East Lemmon Reservoir Report
Nearby: Nelder Ebert No.3 Nelder Ebert No.1
Last Updated: December 6, 2025
East Lemmon is a state-owned earth dam located in South Dakota, specifically in Perkins County.
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Summary
Built in 1930 by the Works Progress Administration (WPA), this dam sits on TR-GRAND river and serves multiple purposes, including flood control and water storage. With a height of 30 feet and a length of 1200 feet, East Lemmon has a normal storage capacity of 1360 acre-feet and a maximum storage capacity of 2600 acre-feet, making it a crucial water resource in the region.
Despite being classified as having a low hazard potential and a moderate risk assessment, East Lemmon is regulated, permitted, inspected, and enforced by the South Dakota Department of Agriculture and Natural Resources (DANR). The dam has an uncontrolled spillway with a width of 125 feet and a drainage area of 88 square miles. While the condition assessment is not rated, the last inspection in November 2018 deemed the dam to be in satisfactory condition. With its strategic location and key role in water management, East Lemmon continues to be a vital infrastructure for the community and the environment.
Managed by the St. Paul District of the US Army Corps of Engineers, East Lemmon contributes to the overall water resource management in the region. With its stone core type and soil foundation, this dam represents a blend of engineering excellence and natural resilience. As climate change continues to impact water resources, East Lemmon stands as a testament to the importance of sustainable infrastructure in mitigating the effects of extreme weather events and ensuring water security for future generations.
Year Completed |
1930 |
Dam Length |
1200 |
Dam Height |
30 |
River Or Stream |
TR-GRAND |
Primary Dam Type |
Earth |
Hydraulic Height |
30 |
Drainage Area |
88 |
Nid Storage |
2600 |
Outlet Gates |
None |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
30 |
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.
East Lemmon