Henry Holwenger Reservoir Report
Nearby: Maciejewski #1 Troy Lee Hunt
Last Updated: December 13, 2025
Henry Holwenger is a privately owned dam located in Bullhead, South Dakota, on the TR-Rock Creek.
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Summary
Built in 1940, this earth dam stands at a height of 19 feet and has a length of 1000 feet, providing a storage capacity of 144 acre-feet. The dam is regulated by the South Dakota Department of Environment and Natural Resources (DENR) and is rated as having a significant hazard potential.
Despite being privately owned, Henry Holwenger is subject to state regulation, permitting, inspection, and enforcement, ensuring that it meets safety standards. The dam's primary purpose and associated structures are not specified, but its key features include a spillway width and outlet gates. With a maximum discharge capacity of 6240 cubic feet per second, this dam plays a crucial role in managing water resources and mitigating flood risks in the area.
For water resource and climate enthusiasts, Henry Holwenger is a noteworthy structure that contributes to water management in Corson County, South Dakota. Its historical significance, construction specifications, and regulatory oversight make it a compelling case study for understanding the intersection of private ownership, state regulations, and dam safety in the context of changing climate conditions.
Year Completed |
1940 |
Dam Length |
1000 |
Dam Height |
19 |
River Or Stream |
TR-ROCK CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
19 |
Nid Storage |
144 |
Hazard Potential |
Significant |
Nid Height |
19 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Cedar Creek Nr Raleigh
|
20cfs |
Grand R At Little Eagle Sd
|
47cfs |
Cannonball River Nr Raleigh
|
40cfs |
Oak Cr Near Wakpala Sd
|
10cfs |
Cannonball River At Breien
|
96cfs |
Moreau R Near Whitehorse Sd
|
35cfs |
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.
Henry Holwenger