Raffensperger No. 1 Reservoir Report
Nearby: Jensen No. 4 Iwan No.1
Last Updated: December 8, 2025
Raffensperger No.
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Summary
1 is a privately owned dam located in Mellette, South Dakota, along the tributary of Pine Creek. Built in 1965, this Earth-type dam stands at a height of 25 feet and spans a length of 335 feet, with a maximum storage capacity of 22 acre-feet. While the dam has a low hazard potential, its condition assessment is currently listed as "Not Rated."
Managed by the South Dakota Department of Environment and Natural Resources (DENR), Raffensperger No. 1 is subject to state regulations, permitting, inspection, and enforcement. It is situated within the jurisdiction of St. Paul District of the US Army Corps of Engineers, and its operations are not funded or overseen by federal agencies. Despite lacking an official Emergency Action Plan (EAP) and risk assessment, the dam remains a critical infrastructure for water resource management in the region, with a maximum discharge capacity of 500 cubic feet per second.
For water resource and climate enthusiasts, Raffensperger No. 1 presents an intriguing case study of a privately owned dam with state regulatory oversight. With its modest size and low hazard potential, this structure serves as a vital component of the local water management system. As efforts to address climate change and ensure the safety of dams continue to evolve, the condition and management of Raffensperger No. 1 offer valuable insights into the intersection of water resource management and infrastructure resilience.
Year Completed |
1965 |
Dam Length |
335 |
Dam Height |
25 |
River Or Stream |
TRIB. PINE CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
25 |
Nid Storage |
22 |
Hazard Potential |
Low |
Nid Height |
25 |
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.
Raffensperger No. 1