Gary Larson Dam Reservoir Report
Nearby: Rudolph Larson Joe Wunder
Last Updated: December 6, 2025
Gary Larson Dam, located in Perkins County, South Dakota, is a privately owned earth dam built in 1951 by the Natural Resources Conservation Service.
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Summary
Standing at a height of 22 feet and with a length of 300 feet, the dam holds a storage capacity of 800 acre-feet. It serves the primary purpose of regulating the flow of the TR Moreau River, with a drainage area of 94 square miles and a maximum discharge capacity of 15,652 cubic feet per second.
Despite being categorized as having a low hazard potential, the condition of Gary Larson Dam is currently not rated as it has not undergone a recent assessment since its last inspection in April 1980. The dam is state-regulated with inspection, permitting, and enforcement responsibilities falling under the South Dakota Department of Agriculture and Natural Resources. While the dam's Emergency Action Plan status and risk management measures are unspecified, its purpose of flood control and water storage highlights its crucial role in water resource management and climate resilience in the region.
As a key infrastructure in the St. Paul District of the US Army Corps of Engineers, Gary Larson Dam plays a vital role in mitigating flood risks and providing water storage for agricultural and environmental purposes in the area. With its historical significance dating back to the mid-20th century, the dam stands as a testament to the engineering efforts in water resource management and highlights the importance of continued monitoring and maintenance to ensure its safety and functionality for the surrounding community and ecosystem.
Year Completed |
1951 |
Dam Length |
300 |
Dam Height |
22 |
River Or Stream |
TR MOREAU RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
22 |
Drainage Area |
94 |
Nid Storage |
800 |
Hazard Potential |
Low |
Nid Height |
22 |
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.
Gary Larson Dam