Dejong Bros 1 Reservoir Report
Nearby: Orl Walcott #1 Larson Dam
Last Updated: December 13, 2025
Dejong Bros 1 is a private dam located in Lyman, South Dakota, along the White River off stream.
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Summary
Constructed in 1961 by the Natural Resources Conservation Service, this earth dam stands at a height of 32 feet and spans a length of 341 feet. With a storage capacity of 64 acre-feet, the dam serves multiple purposes, including flood control, water storage, and irrigation support for the surrounding area.
Managed by the South Dakota Department of Environment and Natural Resources, Dejong Bros 1 is regulated, permitted, inspected, and enforced to ensure its safety and functionality. Despite being rated as low hazard potential and in not rated condition assessment, the dam has not been recently inspected and lacks emergency preparedness measures such as an Emergency Action Plan (EAP) or updated contacts. The presence of this dam contributes to the overall water resource management in the region and highlights the importance of maintaining and monitoring such critical infrastructure for the community's safety and well-being.
Year Completed |
1961 |
Dam Length |
341 |
Dam Height |
32 |
River Or Stream |
WHITE RIVER OFF STREAM |
Primary Dam Type |
Earth |
Hydraulic Height |
32 |
Nid Storage |
64 |
Hazard Potential |
Low |
Nid Height |
32 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
White R Near Oacoma Sd
|
105cfs |
Platte Creek Near Platte
|
3cfs |
Keya Paha R At Wewela Sd
|
54cfs |
Keya Paha R Near Keyapaha Sd
|
33cfs |
White River Near White River
|
42cfs |
Little White R Below White River Sd
|
141cfs |
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.
Dejong Bros 1