Cooper Dam Reservoir Report
Nearby: Ortman Dam Wieman Dam
Last Updated: December 13, 2025
Cooper Dam, located in McCook, South Dakota, is a privately owned structure built in 1997 along the TR-W.
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Summary
Fork Vermillion River. With a height of 21 feet and a length of 240 feet, the dam serves the primary purpose of water resource management, providing a storage capacity of 60 acre-feet. Despite its low hazard potential and moderate risk assessment, the dam is not currently rated for its condition and does not have an emergency action plan in place.
As a state-regulated structure, Cooper Dam falls under the jurisdiction of the South Dakota Department of Environment and Natural Resources (DENR), with permitting, inspection, and enforcement responsibilities carried out by state agencies. The dam features an uncontrolled spillway with a width of 70 feet and a maximum discharge capacity of 945 cfs. While the dam does not have outlet gates or associated locks, it plays a crucial role in managing the flow of the river and protecting downstream areas from flooding.
For water resource and climate enthusiasts, Cooper Dam offers a fascinating example of earth dam construction and its role in maintaining water levels in the region. With its moderate risk assessment and low hazard potential, the dam represents a key piece of infrastructure in the St. Paul District, providing valuable storage capacity for the TR-W. Fork Vermillion River watershed. Despite its current condition assessment status and lack of an emergency action plan, Cooper Dam remains an essential component of the state's water management system, ensuring the safety and security of communities downstream.
Year Completed |
1997 |
Dam Length |
240 |
Dam Height |
21 |
River Or Stream |
TR-W. FORK VERMILLION RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
21 |
Drainage Area |
1 |
Nid Storage |
60 |
Outlet Gates |
None |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
21 |
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.
Cooper Dam