Dannie Oconnell Reservoir Report
Nearby: Sd Noname 276 Sd Noname 274
Last Updated: December 6, 2025
Dannie Oconnell, a privately owned dam located in Pennington, South Dakota, is regulated by the Department of Environment and Natural Resources (DENR).
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Summary
Constructed in 1960, this earth dam stands at a height of 20 feet and spans 635 feet in length, with a storage capacity of 100 acre-feet. The dam serves the primary purpose of water resource management along the TR CHEYENNE river, with a maximum discharge capacity of 950 cubic feet per second.
Despite being categorized as having a low hazard potential, Dannie Oconnell has not been rated for its current condition. The dam does not have an Emergency Action Plan (EAP) in place, and there is no information available regarding the last inspection or maintenance date. As a structure owned by a private entity, it is not under the jurisdiction of any federal agencies but was designed by the Natural Resources Conservation Service. While the risk assessment and management measures for this dam remain unknown, its presence contributes to the overall water infrastructure in South Dakota.
For water resource and climate enthusiasts, Dannie Oconnell offers a glimpse into the diverse landscape of dam infrastructure in the United States. With its historical significance and role in water management, this privately owned structure underscores the importance of regulatory oversight and maintenance to ensure the safety and effectiveness of such critical infrastructure. As climate change continues to impact water resources, understanding the condition and management of dams like Dannie Oconnell becomes increasingly vital for sustainable water resource management in the face of evolving environmental challenges.
Year Completed |
1960 |
Dam Length |
635 |
Dam Height |
20 |
River Or Stream |
TR CHEYENNE |
Primary Dam Type |
Earth |
Hydraulic Height |
20 |
Nid Storage |
100 |
Hazard Potential |
Low |
Nid Height |
20 |
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.
Dannie Oconnell