Wendell Gilman Reservoir Report

Last Updated: December 13, 2025

Wendell Gilman Dam, located in Lyman, South Dakota, is a privately owned structure that was completed in 1961.


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Summary

This earth dam stands at a height of 26 feet and has a length of 294 feet, with a primary purpose that is currently unspecified. The dam has a low hazard potential and is not currently rated in terms of its condition assessment.

Managed by the Natural Resources Conservation Service, Wendell Gilman Dam is regulated by the South Dakota Department of Environment and Natural Resources. It is subject to state permitting, inspection, and enforcement, indicating a commitment to ensuring the safety and integrity of the structure. The dam is situated on the TR-MISSONot RatedI river or stream, within the jurisdiction of the St. Paul District of the US Army Corps of Engineers.

Despite its age, Wendell Gilman Dam continues to serve its purpose of water resource management, with a storage capacity of 26 acre-feet. With its low hazard potential and state-regulated status, this dam represents a key component in the local water infrastructure, providing essential services for the surrounding community while also contributing to the broader efforts in climate resilience and environmental conservation.

Year Completed

1961

Dam Length

294

Dam Height

26

River Or Stream

TR-MISSONot RatedI

Primary Dam Type

Earth

Hydraulic Height

26

Nid Storage

26

Hazard Potential

Low

Nid Height

26
       
Seasonal Comparison

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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.