Rahn Lake Dam Reservoir Report
Nearby: Richey Dam Woolhizer Dam
Last Updated: December 13, 2025
Rahn Lake Dam, located in Tripp, South Dakota, is a state-regulated earth dam completed in 1936 for off-stream water storage from the Niobrara River.
°F
°F
mph
Wind
%
Humidity
Summary
Standing at a height of 22 feet and a length of 570 feet, the dam has a storage capacity of 891 acre-feet, with a normal storage level of 320 acre-feet. Despite being classified as low hazard potential and not currently rated for condition assessment, the dam undergoes regular inspections every three years to ensure its structural integrity and safety.
Managed by the South Dakota Department of Agriculture and Natural Resources (DANR), Rahn Lake Dam plays a crucial role in water resource management in the region, providing water storage for irrigation, recreational activities, and wildlife habitat. The dam's maximum discharge capacity of 2000 cubic feet per second ensures controlled water release during heavy rainfall events, reducing the risk of downstream flooding. With its strategic location and vital functions, Rahn Lake Dam serves as a key component in the overall water infrastructure of the area, safeguarding against water scarcity and promoting sustainable water use practices.
As climate change continues to impact water availability and quality, the maintenance and monitoring of dams like Rahn Lake Dam become increasingly important. By adhering to state regulations for inspection, enforcement, and permitting, the responsible management of this earth dam ensures the long-term resilience of water resources in the region. With a commitment to safety, efficiency, and environmental stewardship, Rahn Lake Dam stands as a testament to effective water resource management in the face of changing climatic conditions.
Year Completed |
1936 |
Dam Length |
570 |
Dam Height |
22 |
River Or Stream |
NIOBRARA RIVER OFF STREAM |
Primary Dam Type |
Earth |
Hydraulic Height |
22 |
Nid Storage |
891 |
Hazard Potential |
Low |
Nid Height |
22 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Keya Paha R At Wewela Sd
|
54cfs |
Keya Paha R Near Keyapaha Sd
|
33cfs |
Long Pine Creek Near Riverview
|
191cfs |
Niobrara River Near Sparks
|
969cfs |
Niobrara River At Mariaville
|
1650cfs |
Platte Creek Near Platte
|
3cfs |
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.
Rahn Lake Dam