Gary Larson Reservoir Report
Nearby: John Penor Rowbotham Dam
Last Updated: December 6, 2025
Gary Larson is a private dam located in Perkins, South Dakota, along the TR MOREAU RIVER.
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Summary
Built in 1952 by the Natural Resources Conservation Service, this earth dam stands at 18 feet high and spans 450 feet in length. With a storage capacity of 120 acre-feet and a maximum discharge of 250 cubic feet per second, Gary Larson serves as a crucial water resource for the area.
Despite its age, Gary Larson is classified as having a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment. While the dam is regulated and permitted by the South Dakota Department of Environment and Natural Resources, it has not undergone recent inspections or evaluations. The dam's emergency action plan status, risk assessment, and inundation maps remain unknown, highlighting the need for continued monitoring and maintenance to ensure the safety and longevity of this vital water infrastructure.
As a significant feature of the local water management system, Gary Larson plays a crucial role in providing water storage and flood control along the TR MOREAU RIVER. With its strategic location and capacity, the dam serves as a valuable resource for the surrounding community and underscores the importance of proactive management and upkeep to safeguard against potential risks and ensure the continued reliability of this essential water infrastructure in South Dakota.
Year Completed |
1952 |
Dam Length |
450 |
Dam Height |
18 |
River Or Stream |
TR MOREAU RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
18 |
Nid Storage |
120 |
Hazard Potential |
Low |
Nid Height |
18 |
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