Jean Simon No.1 Reservoir Report
Nearby: Ray Haberman Sr No.1 Dick Simon No.1
Last Updated: December 13, 2025
Jean Simon No.1 is a privately owned earth dam located in Dewey, South Dakota, along the TR MOREAU river.
°F
°F
mph
Wind
%
Humidity
Summary
Constructed in 1950 by the Natural Resources Conservation Service, this dam stands at a height of 26 feet and has a storage capacity of 100 acre-feet. With a low hazard potential rating and a condition assessment of "Not Rated," Jean Simon No.1 serves as a vital water resource infrastructure in the region, providing flood control and water storage benefits to the local community.
Despite its age, Jean Simon No.1 remains regulated by the South Dakota Department of Environment and Natural Resources, with state permitting, inspection, and enforcement activities in place to ensure its safety and functionality. The dam has a maximum discharge capacity of 600 cubic feet per second and a normal storage level of 42 acre-feet. While the dam has not been rated for its condition, its low hazard potential suggests that it poses minimal risk to downstream areas in the event of a failure, highlighting the importance of ongoing monitoring and maintenance efforts.
Although lacking detailed information on emergency preparedness measures such as an Emergency Action Plan (EAP), Jean Simon No.1 continues to play a crucial role in managing water resources in the region. With its strategic location and design features, this dam represents a key component of the local water infrastructure, supporting agricultural, recreational, and environmental needs in Dewey County and beyond. As climate change impacts water availability and quality, the maintenance and operation of dams like Jean Simon No.1 become increasingly essential in ensuring a sustainable and resilient water supply for future generations.
Year Completed |
1950 |
Dam Length |
400 |
Dam Height |
26 |
River Or Stream |
TR MOREAU |
Primary Dam Type |
Earth |
Hydraulic Height |
26 |
Nid Storage |
100 |
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 |
Cheyenne R Near Plainview Sd
|
0cfs |
Bad R Near Fort Pierre Sd
|
7cfs |
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.
Jean Simon No.1