Johnson Lake Dam Reservoir Report
Nearby: 4th July Tank Dam Cometa Lake Dam
Last Updated: December 12, 2025
Johnson Lake Dam, located in Zavala, Texas, on Chaparrosa Creek, is a privately owned Earth dam primarily used for irrigation purposes.
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Summary
Built in 1966 by LOCKWOOD ANDREWS & NEWMAN, the dam stands at a height of 21 feet and has a storage capacity of 420 acre-feet. Despite being a non-federally regulated structure, the dam has undergone state inspections and permitting to ensure its safety and functionality.
With a spillway type of "None" and a hazard potential of "Not Available," Johnson Lake Dam presents a unique profile in terms of risk assessment. Even though its condition has not been rated, the dam is categorized as having a high risk level (2). Emergency action plans and inundation maps have not been prepared for this structure, raising potential concerns in the event of a dam failure. However, the dam has not been modified since its completion, indicating a stable operational history.
Despite its lack of federal oversight, Johnson Lake Dam serves as a vital resource for irrigation in the region. As climate change continues to impact water resources, the management and monitoring of dams like Johnson Lake become increasingly important to ensure the safety and sustainability of water supplies for agriculture and other purposes. It is essential for private dam owners to collaborate with state agencies to implement best practices for dam safety and emergency preparedness to mitigate risks and protect surrounding communities.
Year Completed |
1966 |
Dam Length |
1350 |
Dam Height |
21 |
River Or Stream |
CHAPARROSA CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
21 |
Nid Storage |
420 |
Structural Height |
21 |
Outlet Gates |
None - 1 |
Hazard Potential |
Not Available |
Foundations |
Unlisted/Unknown |
Nid Height |
21 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Johnson Lake Dam