Old Mill Lake Dam Reservoir Report

Last Updated: December 5, 2025

Old Mill Lake Dam, located in Granite Falls, North Carolina, is a concrete structure on Gunpowder Creek with a hydraulic height of 50 feet and a structural height of 53 feet.


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Summary

Built for purposes other than flood control or hydroelectric power generation, the dam has a storage capacity of 2,415 acre-feet and covers a surface area of 81 acres, serving as a vital water resource in Caldwell County. However, recent inspections have raised concerns about its safety, as it has been rated as having a high hazard potential and poor condition.

Managed by a private owner, Old Mill Lake Dam falls under the regulatory oversight of the North Carolina Department of Environmental Quality's Dam Safety Program. Despite being state-regulated and regularly inspected, the dam's poor condition calls for immediate attention and potential risk management measures. With the hazard potential deemed high, stakeholders and the local community must ensure that emergency action plans are in place and that the dam meets safety guidelines to prevent any potential disasters. As water resource and climate enthusiasts, it is crucial to monitor the situation closely and advocate for necessary repairs or upgrades to safeguard this essential infrastructure.

Dam Length

265

River Or Stream

Gunpowder Creek

Primary Dam Type

Concrete

Surface Area

81

Hydraulic Height

50

Drainage Area

22336

Nid Storage

2415

Structural Height

53

Hazard Potential

High

Nid Height

53
       
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.