Rank Dam Reservoir Report

Last Updated: December 12, 2025

Rank Dam, located in Buffalo, South Dakota, is a privately owned structure designed by the Civilian Conservation Corps in 1935.


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Summary

It stands at a height of 40 feet and spans a length of 740 feet, with a storage capacity of 1340 acre-feet. With a drainage area of 5 square miles, the dam has a maximum discharge rate of 3102 cubic feet per second and features an uncontrolled spillway that is 120 feet wide.

Despite its historical significance and vital role in water resource management, Rank Dam is currently assessed to be in poor condition with a high hazard potential. The last inspection in 2017 reported the dam's structural integrity to be compromised, highlighting the urgent need for maintenance and rehabilitation. The risk assessment categorizes the dam as having a moderate risk level, indicating the importance of implementing proper risk management measures to ensure public safety and environmental protection.

Water resource and climate enthusiasts should take note of Rank Dam's critical condition and the associated risks it poses. As a key component of the local infrastructure, efforts must be made to address the dam's maintenance needs and ensure its long-term stability. With its rich history and significant impact on the surrounding area, Rank Dam serves as a reminder of the importance of proactive management and investment in sustainable water resource infrastructure.

Year Completed

1935

Dam Length

740

Dam Height

40

River Or Stream

TR-MISSONot RatedI

Primary Dam Type

Earth

Hydraulic Height

40

Drainage Area

5

Nid Storage

1340

Outlet Gates

None

Hazard Potential

High

Foundations

Soil

Nid Height

40
       
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.