Evans No.2 Reservoir Report

Last Updated: December 5, 2025

Evans No.2 is a privately owned dam located in Custer, South Dakota, along the TR-CHEYENNE river.


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Summary

Built in 1960 by the Natural Resources Conservation Service, this earth dam stands at a height of 15 feet and has a length of 555 feet, providing a storage capacity of 50 acre-feet. Despite its low hazard potential and unassessed condition, the dam is regulated, permitted, inspected, and enforced by the South Dakota Department of Environment and Natural Resources.

With a maximum discharge of 900 cubic feet per second, Evans No.2 serves a crucial role in water resource management in the region. Although the dam's emergency action plan is not currently rated or updated, the structure meets regulatory guidelines and is in compliance with state jurisdiction. The dam's purpose, aside from flood control and irrigation, remains unspecified, but its presence underscores the importance of infrastructure in mitigating the impacts of climate change on water resources.

As climate change continues to alter precipitation patterns and increase the frequency of extreme weather events, the maintenance and monitoring of dams like Evans No.2 are essential for safeguarding communities and ecosystems downstream. By recognizing the significance of this earth dam in the context of water resource management and climate resilience, enthusiasts can appreciate the intersection of infrastructure, regulation, and environmental stewardship in ensuring the sustainability of our water systems.

Year Completed

1960

Dam Length

555

Dam Height

15

River Or Stream

TR-CHEYENNE

Primary Dam Type

Earth

Hydraulic Height

15

Nid Storage

50

Hazard Potential

Low

Nid Height

15
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.