Thorstensen 1 Reservoir Report
Nearby: Fred Joens Thorstensen 2
Last Updated: December 13, 2025
Thorstensen 1 is a privately owned dam located in Dewey County, South Dakota, along the TR-MOREAU river.
°F
°F
mph
Wind
%
Humidity
Summary
The dam, completed in 1968, stands at a height of 26 feet and has a storage capacity of 23 acre-feet. While the dam is classified as an Earth type, it is regulated by the South Dakota Department of Environment and Natural Resources (DENR) and undergoes regular inspections, permitting, and enforcement to ensure its safety and compliance with state regulations.
Despite its low hazard potential and a condition assessment of "Not Rated," Thorstensen 1 plays a crucial role in water resource management and flood control in the region. The dam has a maximum discharge capacity of 1540 cubic feet per second and serves to protect the surrounding area from potential inundation and water-related risks. While the dam's emergency action plan status and risk assessment details are currently unknown, its presence signifies a commitment to safeguarding water resources and adapting to the impacts of climate change in the area.
As a key component of the St. Paul District's infrastructure in South Dakota, Thorstensen 1, under the ownership of a private entity, underscores the collaborative efforts between public agencies and private stakeholders in managing water resources effectively. With its strategic location and operational history, the dam serves as a vital asset in maintaining the ecological balance and resilience of the TR-MOREAU river basin, highlighting the importance of sustainable water resource management in the face of evolving climate challenges.
Year Completed |
1968 |
Dam Length |
320 |
Dam Height |
26 |
River Or Stream |
TR-MOREAU |
Primary Dam Type |
Earth |
Hydraulic Height |
26 |
Nid Storage |
23 |
Hazard Potential |
Low |
Nid Height |
26 |
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 |
Cedar Creek Nr Raleigh
|
20cfs |
Cannonball River Nr Raleigh
|
40cfs |
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 1