Major Lake Reservoir Report

Last Updated: December 5, 2025

Major Lake, located in Hill City, South Dakota, is a federal-owned water resource managed by the USDA Forest Service.


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Summary

Built in 1939, this recreational lake serves as a fish and wildlife pond, providing a serene escape for visitors to enjoy outdoor activities. With a dam height of 13 feet and a storage capacity of 73 acre-feet, Major Lake covers a drainage area of 32 acres and has a maximum discharge rate of 1030 cubic feet per second.

Despite its relatively small surface area, Major Lake poses a high hazard potential due to its uncontrolled spillway and outlet gates. The dam's condition assessment is currently not rated, reflecting the need for regular inspections and potential risk management measures to ensure public safety. The lake's risk assessment indicates a moderate level of risk, emphasizing the importance of emergency preparedness in case of unforeseen events. While the lake's inundation maps and emergency action plan status are unclear, there is a need for ongoing monitoring and adherence to safety guidelines to mitigate potential risks.

In the picturesque landscape of Pennington County, Major Lake stands as a valuable recreational and ecological asset, attracting both locals and tourists alike. As climate change continues to impact water resources, the conservation and sustainable management of Major Lake will be crucial in preserving its natural beauty and recreational opportunities for future generations. With a focus on safety, risk assessment, and environmental stewardship, Major Lake remains a prominent destination for water resource and climate enthusiasts seeking to experience the unique blend of nature and recreation in South Dakota.

Year Completed

1939

Dam Length

310

Dam Height

13

River Or Stream

SPRING CR TRIB

Primary Dam Type

Earth

Hydraulic Height

8

Drainage Area

32

Nid Storage

73

Structural Height

18

Outlet Gates

Uncontrolled

Hazard Potential

High

Nid Height

18
       
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.