Thorstensen 2 Reservoir Report
Nearby: Fred Joens Thorstensen 1
Last Updated: December 13, 2025
Thorstensen 2 is a privately owned earth dam located in Dewey, South Dakota, along the TR-MOREAU river.
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Summary
Built in 1972, this dam stands at a height of 28 feet and has a storage capacity of 21 acre-feet. With a low hazard potential and a "Not Rated" condition assessment, Thorstensen 2 plays a crucial role in managing water resources in the area.
Managed by the South Dakota Department of Environment and Natural Resources (DENR), this dam is subject to state regulations, permitting, inspection, and enforcement. Despite its relatively small size, Thorstensen 2 serves important functions for flood control, water storage, and potentially irrigation in the region. With a maximum discharge capacity of 920 cubic feet per second, this dam helps mitigate the impact of extreme weather events on the surrounding communities.
The presence of Thorstensen 2 underscores the significance of small-scale water infrastructure in maintaining water security and climate resilience. As climate change continues to impact the frequency and intensity of extreme weather events, dams like Thorstensen 2 play a vital role in safeguarding communities and ecosystems against floods and droughts. With proper management and maintenance, this dam will continue to contribute to sustainable water resource management in the region.
Year Completed |
1972 |
Dam Length |
200 |
Dam Height |
28 |
River Or Stream |
TR-MOREAU |
Primary Dam Type |
Earth |
Hydraulic Height |
28 |
Nid Storage |
21 |
Hazard Potential |
Low |
Nid Height |
28 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Moreau R Near Whitehorse Sd
|
35cfs |
Grand R At Little Eagle Sd
|
47cfs |
Oak Cr Near Wakpala Sd
|
10cfs |
Moreau R Near Faith Sd
|
14cfs |
Cheyenne R Near Plainview Sd
|
0cfs |
Cedar Creek Nr Raleigh
|
20cfs |
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.
Thorstensen 2