May Dam Reservoir Report
Nearby: Green Valley May & Sons Dam
Last Updated: December 13, 2025
May Dam, located in Jackson, South Dakota, is a privately owned earth dam that spans 400 feet in length and stands at a height of 24 feet.
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Summary
Completed in 1947, this dam on Potato Creek has a storage capacity of 125 acre-feet, with a maximum discharge of 1,500 cubic feet per second. Despite its low hazard potential and a current condition assessment of "Not Rated," the dam is regulated by the South Dakota Department of Environment and Natural Resources, with state permitting, inspection, and enforcement in place.
Operated by the Natural Resources Conservation Service, May Dam plays a crucial role in water resource management in the region. While specific purposes for the dam are not listed, its primary function as an earth structure demonstrates its importance in flood control, water supply, and environmental conservation. The dam's presence also contributes to the overall ecosystem health of the area, providing benefits beyond its immediate water storage capacity.
As a point of interest for water resource and climate enthusiasts, May Dam serves as a testament to the intersection of human infrastructure and natural ecosystems. With its historical significance and ongoing regulatory oversight, the dam represents a balance between harnessing water resources for societal needs and maintaining the integrity of the surrounding environment. Its location in the St. Paul District, with Congressman Dusty Johnson representing the area, highlights the interconnectedness of water management, government oversight, and community engagement in sustaining critical infrastructure for the benefit of all stakeholders.
Year Completed |
1947 |
Dam Length |
400 |
Dam Height |
24 |
River Or Stream |
POTATO CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
24 |
Nid Storage |
125 |
Hazard Potential |
Low |
Nid Height |
24 |
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.
May Dam