Harrison No.1 Reservoir Report

Last Updated: December 5, 2025

Harrison No.1 is a privately owned earth dam located in Custer, South Dakota, along the TR-CHEYENNE river.


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Summary

Built in 1959, this dam stands at a height of 23 feet and has a length of 450 feet, providing a maximum storage capacity of 92 acre-feet. Despite its low hazard potential, the dam is regulated and inspected by the South Dakota Department of Environment and Natural Resources, ensuring its safety and compliance with state regulations.

Managed by the Natural Resources Conservation Service, Harrison No.1 plays a crucial role in water resource management in the region. With a normal storage capacity of 53 acre-feet and a maximum discharge of 2100 cubic feet per second, this dam serves as a vital structure for maintaining water supply and flood control along the TR-CHEYENNE river. While the dam's condition assessment is currently listed as "Not Rated," regular inspections and enforcement by state authorities help to ensure its continued functionality and safety for the surrounding community.

As a key component of the local water infrastructure, Harrison No.1 contributes to the overall resiliency of the area in the face of changing climate patterns. Its presence underscores the importance of proactive dam management and emergency preparedness in safeguarding water resources and mitigating potential risks. With a commitment to regulatory compliance and safety measures, this dam serves as a valuable asset for water resource and climate enthusiasts alike.

Year Completed

1959

Dam Length

450

Dam Height

23

River Or Stream

TR-CHEYENNE

Primary Dam Type

Earth

Hydraulic Height

23

Nid Storage

92

Hazard Potential

Low

Nid Height

23
       
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.