Koskan Reservoir Report
Nearby: Eckland A.W. No.1 Eklund No.5
Last Updated: December 12, 2025
Koskan is a privately owned earth dam located in Mellette, South Dakota, built in 1956.
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Summary
This dam stands at a height of 22 feet and has a length of 342 feet, providing a storage capacity of 55 acre-feet. It is situated on the TR. Big White Offstream water source and is regulated by the South Dakota Department of Environment and Natural Resources (DENR). The dam has a low hazard potential and is currently rated as "Not Rated" in terms of its condition assessment.
Despite being a relatively small structure, Koskan plays a crucial role in water resource management within the region. Its presence helps to regulate water flow, provide storage capacity, and contribute to overall water security in the area. As climate change continues to impact water resources, dams like Koskan will become increasingly important in ensuring sustainable water management practices and mitigating the effects of extreme weather events.
With its state-regulated status and adherence to inspection, permitting, and enforcement protocols, Koskan demonstrates a commitment to safety and environmental responsibility. As water resource enthusiasts and climate advocates, staying informed about the condition and management of dams like Koskan is essential for understanding and addressing the challenges posed by a changing climate on our water resources. By supporting ongoing monitoring and maintenance efforts for structures like Koskan, we can work towards a more resilient and sustainable water future.
Year Completed |
1956 |
Dam Length |
342 |
Dam Height |
22 |
River Or Stream |
TR. BIG WHITE OFFSTREAM |
Primary Dam Type |
Earth |
Hydraulic Height |
22 |
Nid Storage |
55 |
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.
Koskan