Jans 1 Reservoir Report
Nearby: Ryno #2 Van Collons No.1
Last Updated: December 12, 2025
Jans 1 is a private dam located in Mellette, South Dakota, with a height of 32 feet and a length of 750 feet.
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Summary
It was completed in 1936 and serves as a vital structure for regulating water flow on the tributary of White Thunder Creek. The dam has a storage capacity of 115 acre-feet and a maximum discharge of 1397 cubic feet per second, making it an essential resource for water management in the area.
Despite its age, Jans 1 has a low hazard potential and is currently rated as "Not Rated" in terms of its condition assessment. The dam is regulated and inspected by the South Dakota Department of Environment and Natural Resources (DENR), ensuring that it meets all necessary safety standards. While there are no associated structures or emergency action plans in place for Jans 1, it continues to play a crucial role in water resource management and climate resilience efforts in the region.
With its strategic location and capacity to store and regulate water flow, Jans 1 is a key player in maintaining water security and mitigating the impacts of climate change in Mellette, South Dakota. As water resource and climate enthusiasts, it is important to monitor the condition and performance of dams like Jans 1 to ensure their continued effectiveness in safeguarding communities and ecosystems against the challenges of a changing climate.
Year Completed |
1936 |
Dam Length |
750 |
Dam Height |
32 |
River Or Stream |
TRIB. WHITE THUNDER CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
32 |
Nid Storage |
115 |
Hazard Potential |
Low |
Nid Height |
32 |
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.
Jans 1