Johnson Lake Dam Reservoir Report

Last Updated: December 5, 2025

Johnson Lake Dam in Ellis, Texas, built in 1964, stands as a testament to sustainable water resource management and climate resiliency.


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Summary

With a primary purpose of recreation, this private Earth dam on the Hare Prong river boasts a structural height of 20 feet and a length of 800 feet. While its NID storage capacity reaches 800 acre-feet, the normal storage level sits at 144 acre-feet, covering a surface area of 30 acres.

Managed by the Texas Commission on Environmental Quality (TCEQ), Johnson Lake Dam has withstood the test of time, undergoing state inspection, permitting, and enforcement. Despite its high hazard potential, the dam is not currently rated for its condition assessment, hinting at the need for further evaluation and risk management measures. With no spillway and limited drainage area, the dam presents a unique challenge for emergency preparedness and response.

As water resource and climate enthusiasts, the captivating story of Johnson Lake Dam intertwines elements of history, engineering, and environmental stewardship. This recreational gem in Ellis County serves as a reminder of the delicate balance between human intervention and nature's forces, urging us to prioritize sustainable infrastructure development and resilience in the face of changing climate patterns.

Year Completed

1964

Dam Length

800

Dam Height

20

River Or Stream

HARE PRONG

Primary Dam Type

Earth

Surface Area

30

Hydraulic Height

20

Nid Storage

800

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.