Long Hollow Dam Reservoir Report
Nearby: Fishko Dam #3 Fishko Dam
Last Updated: December 6, 2025
Long Hollow Dam, located in Fall River, South Dakota, is a privately owned structure that has been regulating the flow of the TR Cheyenne River since its completion in 1947.
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Summary
Standing at a height of 24 feet and with a length of 2000 feet, the earth dam has a storage capacity of 576 acre-feet and a maximum discharge of 33,000 cubic feet per second. Despite its low hazard potential, the dam is state-regulated and subject to regular inspections, permitting, and enforcement by the South Dakota Department of Environment and Natural Resources.
Although Long Hollow Dam's primary purpose is not specified, its importance in water resource management and flood control cannot be understated. The dam plays a crucial role in maintaining a steady water supply and mitigating potential flooding risks in the region. With a condition assessment of "Not Rated" and no Emergency Action Plan currently prepared, there is room for improvement in ensuring the safety and efficiency of this essential infrastructure.
As water resource and climate enthusiasts, understanding the significance of Long Hollow Dam in the local ecosystem and community is essential. With its strategic location and modest storage capacity, the dam serves as a vital component in the management of water resources in South Dakota. Continued monitoring and maintenance efforts will be key to preserving the integrity of this structure and maximizing its benefits for both humans and the environment.
Year Completed |
1947 |
Dam Length |
2000 |
Dam Height |
24 |
River Or Stream |
TR CHEYENNE |
Primary Dam Type |
Earth |
Hydraulic Height |
24 |
Nid Storage |
576 |
Hazard Potential |
Low |
Nid Height |
24 |
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.
Long Hollow Dam