Lake Hanson Reservoir Report
Nearby: Moench Dam Ethan
Last Updated: December 13, 2025
Lake Hanson, located in Hanson, South Dakota, is a state-regulated earthen dam constructed in 1932 by the Works Progress Administration (WPA).
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Summary
With a maximum storage capacity of 340 acre-feet and a normal storage capacity of 250 acre-feet, the dam stands at a height of 24 feet and stretches 780 feet in length. The dam's primary purpose is to control the flow of the TR-JAMES river, with a maximum discharge capacity of 420 cubic feet per second.
Despite being categorized as having a low hazard potential and a moderate risk assessment, Lake Hanson has not been rated for its condition assessment. The dam features an uncontrolled spillway with a width of 20 feet and no outlet gates. The last inspection of Lake Hanson took place in October 2016, with an inspection frequency of every 3 years. The dam is under the jurisdiction of the South Dakota Department of Agriculture and Natural Resources (DANR), which oversees permitting, inspection, and enforcement activities related to the dam. Despite its age, Lake Hanson continues to serve its purpose as a vital water resource for the surrounding area, attracting water resource and climate enthusiasts alike.
Year Completed |
1932 |
Dam Length |
780 |
Dam Height |
24 |
River Or Stream |
TR-JAMES |
Primary Dam Type |
Earth |
Hydraulic Height |
24 |
Nid Storage |
340 |
Outlet Gates |
None |
Hazard Potential |
Low |
Foundations |
Soil |
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.
Lake Hanson