Evans No.1 Reservoir Report
Nearby: Evans No.2 Peterson Dam
Last Updated: December 5, 2025
Evans No.1 is a privately-owned earth dam located in Custer, South Dakota, along the TR-CHEYENNE river.
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Summary
Constructed in 1951 by the Natural Resources Conservation Service, this dam stands at 21 feet high and spans 555 feet in length, providing a maximum storage capacity of 50 acre-feet. With a low hazard potential and a condition assessment of "Not Rated," Evans No.1 plays a crucial role in water resource management in the region.
Despite its age, Evans No.1 remains regulated and inspected by the South Dakota Department of Environment and Natural Resources, ensuring its safety and functionality for water supply and flood control purposes. The dam has a normal storage capacity of 20 acre-feet and can discharge up to 1080 cubic feet per second through its outlet. Although the dam's emergency action plan and risk assessment details are not readily available, its presence and maintenance contribute to the overall water resource infrastructure in the area.
As a vital component of the water management system in Custer, South Dakota, Evans No.1 exemplifies the collaboration between private ownership and state regulatory agencies in ensuring the safety and efficiency of water resources. With its historic significance and continued operation, this earth dam serves as a reminder of the importance of maintaining and monitoring critical infrastructure to address the challenges of climate change and water resource management in the region.
Year Completed |
1951 |
Dam Length |
555 |
Dam Height |
21 |
River Or Stream |
TR-CHEYENNE |
Primary Dam Type |
Earth |
Hydraulic Height |
21 |
Nid Storage |
50 |
Hazard Potential |
Low |
Nid Height |
21 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
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.
Evans No.1