G.P. Joens Reservoir Report
Nearby: F. Joens School Land
Last Updated: December 8, 2025
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Summary
Joens is a privately owned earth dam located in Dewey, South Dakota, along the TR MOREAU river. Built in 1941, this dam stands at a height of 24 feet and has a storage capacity of 162 acre-feet. With a low hazard potential and a condition assessment of "Not Rated," G.P. Joens serves as a vital structure for water resource management in the area.
Managed by the South Dakota Department of Environment and Natural Resources (DENR), G.P. Joens is regulated, permitted, inspected, and enforced to ensure its safe operation. Although the dam has not been rated for its condition, it meets state jurisdiction requirements and plays a key role in flood control and water storage for the region. With a maximum discharge capacity of 2000 cubic feet per second, this dam is equipped to handle significant water flows during peak times.
Overall, G.P. Joens is an essential infrastructure for water resource enthusiasts and climate advocates, showcasing the importance of proper dam management and regulation in ensuring the safety and sustainability of water resources. Its presence along the TR MOREAU river not only contributes to flood control and water storage but also highlights the collaboration between private ownership and state regulatory agencies in maintaining critical water infrastructure.
Year Completed |
1941 |
Dam Length |
700 |
Dam Height |
24 |
River Or Stream |
TR MOREAU |
Primary Dam Type |
Earth |
Hydraulic Height |
24 |
Nid Storage |
162 |
Hazard Potential |
Low |
Nid Height |
24 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Moreau R Near Whitehorse Sd
|
35cfs |
Grand R At Little Eagle Sd
|
47cfs |
Moreau R Near Faith Sd
|
14cfs |
Cheyenne R Near Plainview Sd
|
0cfs |
Oak Cr Near Wakpala Sd
|
10cfs |
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.
G.P. Joens