Johnson Dam No 2 Reservoir Report

Last Updated: December 5, 2025

Located on the North Concho River in Tom Green County, Texas, Johnson Dam No 2 is a buttress-type dam primarily used for recreation.


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Summary

Standing at a height of 20 feet and with a length of 100 feet, the dam was completed in 1931 and has a storage capacity of 150 acre-feet. Despite its age, the dam is still in good condition with a high hazard potential rating.

Managed by the local government and regulated by the Texas Commission on Environmental Quality (TCEQ), Johnson Dam No 2 is a vital water resource in the region. While the dam does not have a spillway, it does have one outlet gate. The dam has not been modified in recent years and its last inspection was conducted in 1979, with a risk assessment rating of high (2).

For water resource and climate enthusiasts, Johnson Dam No 2 presents an interesting case study in dam management and maintenance. With its historical significance and important role in providing recreational opportunities, the dam serves as a reminder of the careful balance required to ensure the safety and sustainability of our water infrastructure in the face of changing climate conditions.

Year Completed

1931

Dam Length

100

Dam Height

20

River Or Stream

NORTH CONCHO RIVER

Primary Dam Type

Buttress

Hydraulic Height

20

Nid Storage

150

Structural Height

20

Outlet Gates

None - 1

Hazard Potential

Not Available

Foundations

Unlisted/Unknown

Nid Height

20
       
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.