Ah Johnson Reservoir Levee Reservoir Report
Last Updated: December 6, 2025
The Ah Johnson Reservoir Levee, located in Matagorda, Texas, was completed in 1971 and serves primarily for irrigation and recreation purposes.
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Summary
This private-owned structure stands at a height of 19 feet and stretches over 14,450 feet in length, with a maximum storage capacity of 562 acre-feet. Situated along the Tres Palacios Creek, this earth dam is supported by a stone core and is regulated and inspected by the Texas Commission on Environmental Quality (TCEQ).
Despite not having a spillway, the reservoir has a hazard potential of "Not Available" and a risk assessment rating of "High (2)". The condition assessment of the dam is currently "Not Rated", with the last inspection conducted in December 1973. While emergency preparedness measures such as an Emergency Action Plan (EAP) and inundation maps are not available, the structure has been deemed to meet regulatory guidelines and is subject to enforcement by state agencies.
This structure, within the jurisdiction of the Fort Worth District of the US Army Corps of Engineers, plays a significant role in water resource management in the region. With its vast surface area and storage capacity, the Ah Johnson Reservoir Levee stands as a key component in the local water infrastructure system, providing essential support for agriculture and recreational activities in the area. Its history, design, and regulatory oversight make it a noteworthy feature for water resource and climate enthusiasts to study and appreciate.
Year Completed |
1971 |
Dam Length |
14450 |
Dam Height |
19 |
River Or Stream |
TRES PALACIOS CREEK |
Primary Dam Type |
Earth |
Surface Area |
74 |
Hydraulic Height |
19 |
Nid Storage |
562 |
Structural Height |
19 |
Outlet Gates |
None - 1 |
Hazard Potential |
Not Available |
Foundations |
Unlisted/Unknown |
Nid Height |
19 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Tres Palacios Rv Nr Midfield
|
44cfs |
Colorado Rv Nr Bay City
|
2670cfs |
E Mustang Ck Nr Louise
|
3cfs |
Colorado Rv Nr Wadsworth
|
481cfs |
W Mustang Ck Nr Ganado
|
6cfs |
Colorado Rv At Wharton
|
333cfs |
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.
Ah Johnson Reservoir Levee