Cumberland Mtn Lake#3 Reservoir Report

Last Updated: December 14, 2025

Cumberland Mtn Lake#3, located in BOST COVE, Grundy, Tennessee, is a privately owned earth dam constructed in 1972 on Mill Creek.


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Summary

With a hydraulic height of 22.2 feet and a structural height of 24.5 feet, this dam stands at a total height of 25 feet and spans 925 feet in length. It has a maximum storage capacity of 384 acre-feet and a normal storage capacity of 302 acre-feet, covering a surface area of 34 acres with a drainage area of 0.39 square miles.

Despite being categorized with a low hazard potential, Cumberland Mtn Lake#3 is rated as moderate in terms of risk assessment. The dam has not been inspected since December 2016, with a scheduled inspection frequency of 5 years. While the condition assessment remains unrated, there is no Emergency Action Plan (EAP) in place, and the dam does not meet regulatory guidelines for inundation maps or emergency contacts. Although there are no associated structures or locks, the dam does have an uncontrolled spillway and outlet gates.

Overall, Cumberland Mtn Lake#3 serves as a significant water resource in Grundy, Tennessee, providing storage for the surrounding area. Climate and water resource enthusiasts may be interested in the engineering and maintenance challenges associated with this privately owned dam, as well as the risk management measures in place to ensure public safety in the event of any emergencies.

Year Completed

1972

Dam Length

925

River Or Stream

MILL CREEK

Primary Dam Type

Earth

Surface Area

34

Hydraulic Height

22.2

Drainage Area

0.39

Nid Storage

384

Structural Height

24.5

Outlet Gates

None

Hazard Potential

Low

Nid Height

25
       
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.