Em Johnson Alum Sludge Lagoon Dam Reservoir Report

Last Updated: December 15, 2025

The Em Johnson Alum Sludge Lagoon Dam, located in Wake County, North Carolina, is a privately owned structure that serves a unique purpose related to water resource management.


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Summary

This Earth-type dam, completed in 1994, has a hydraulic height of 38 feet and a structural height of 41 feet, helping to regulate the flow of Honeycutt Creek-Os. With a storage capacity of 108.3 acre-feet and a normal storage level of 90 acre-feet, this dam plays a vital role in controlling water levels in the area.

Despite its satisfactory condition assessment as of October 2020, the Em Johnson Alum Sludge Lagoon Dam is classified as having a high hazard potential, highlighting the importance of regular inspections and maintenance. The dam's emergency action plan (EAP) was last revised in July 2018, and it meets all necessary guidelines for managing potential risks and emergencies. With a maximum discharge capacity of 190 cubic feet per second, this dam is equipped to handle significant water flow while ensuring the safety of surrounding communities.

The presence of this dam underscores the critical role that infrastructure plays in water resource management and climate resilience efforts. As a key component of the state-regulated system, the Em Johnson Alum Sludge Lagoon Dam represents a commitment to safeguarding water resources and mitigating potential hazards. With ongoing inspections and adherence to regulatory guidelines, this dam continues to serve as a crucial asset in maintaining the ecological balance of the region and protecting against adverse impacts of changing climate conditions.

Year Completed

1994

Dam Length

1600

River Or Stream

Honeycutt Creek-Os

Primary Dam Type

Earth

Surface Area

6

Hydraulic Height

38

Drainage Area

6.5

Nid Storage

108.3

Structural Height

41

Hazard Potential

High

Nid Height

41
       
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.