Neilsen #1 Reservoir Report
Nearby: Strain Ranch No. 1 Greene No. 1
Last Updated: December 9, 2025
Neilsen #1 is a privately owned dam located in Mellette, South Dakota, along TR Cottonwood Creek offstream.
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Summary
The dam, completed in 1968, stands at a height of 35 feet and has a storage capacity of 75 acre-feet. It serves a low hazard potential and has not been rated for its condition assessment. Despite being owned privately, the state of South Dakota regulates and inspects the dam regularly to ensure its safety and compliance with state regulations.
The dam's primary purpose and associated structures are not specified in the data, but it is important to note that the dam plays a crucial role in water resource management in the area. With a maximum discharge capacity of 1037 cubic feet per second, Neilsen #1 helps in controlling water flow and preventing flooding in the region. Its presence also contributes to the overall ecological balance of the surrounding environment, demonstrating the intersection of water resource management and climate resilience in South Dakota.
As a key infrastructure in the state, Neilsen #1 underscores the importance of maintaining and monitoring dams for water resource sustainability and climate adaptation. With its low hazard potential and regulatory oversight by the South Dakota Department of Environment and Natural Resources, the dam serves as a vital component in the local water management system. It is essential for water resource and climate enthusiasts to recognize the significance of structures like Neilsen #1 in ensuring the resilience of communities and ecosystems in the face of changing climate conditions.
Year Completed |
1968 |
Dam Length |
550 |
Dam Height |
35 |
River Or Stream |
TR COTTONWOOD CR OFFSTREAM |
Primary Dam Type |
Earth |
Hydraulic Height |
35 |
Nid Storage |
75 |
Hazard Potential |
Low |
Nid Height |
35 |
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.
Neilsen #1