Lake Johnson Dam Reservoir Report

Last Updated: December 5, 2025

Lake Johnson Dam, located in Wake County, North Carolina, serves as a vital water supply structure for the surrounding area.


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Summary

Built in 1914, this earth dam stands at a hydraulic height of 37 feet and a structural height of 40 feet, with a length of 779 feet. The dam has a storage capacity of 3090 acre-feet, providing essential water resources for the region.

Managed by the local government and regulated by the North Carolina Department of Environmental Quality, Division of Energy, Mineral, and Land Resources, the dam is classified as having a high hazard potential but is currently in fair condition. Regular inspections are conducted every two years to ensure the safety and integrity of the structure. Despite its age, Lake Johnson Dam continues to play a crucial role in water supply management and flood control along Walnut Creek.

With a surface area of 147.5 acres and a drainage area of 4403 acres, Lake Johnson Dam not only provides water storage but also offers recreational opportunities for the community. The dam's presence has helped to mitigate potential flood risks and ensure a reliable water supply for residents in the Raleigh area. As climate change impacts water resources, the maintenance and upkeep of structures like Lake Johnson Dam become increasingly important for sustainable water management in the region.

Year Completed

1914

Dam Length

779

River Or Stream

Walnut Creek

Primary Dam Type

Earth

Surface Area

147.5

Hydraulic Height

37

Drainage Area

4403

Nid Storage

3090

Structural Height

40

Hazard Potential

High

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.