Llano Grande Tank Dam Reservoir Report
Last Updated: December 5, 2025
Llano Grande Tank Dam, located in McMullen, Texas, was completed in 1952 and serves as an important water resource for the area.
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Summary
This earth dam, with a height of 12 feet and a length of 1290 feet, has a maximum storage capacity of 72 acre-feet and a normal storage of 25 acre-feet. While it does not have a spillway, it does have one outlet gate to regulate water flow.
Although the dam is privately owned, it is regulated and permitted by the state of Texas. The primary purpose of Llano Grande Tank Dam is listed as "Other," indicating its importance in managing water resources for various uses. Despite being rated as having a high risk potential, the dam's condition assessment is listed as "Not Rated," suggesting a need for further evaluation and risk management measures. Overall, Llano Grande Tank Dam plays a crucial role in water management in the area and is a key feature for water resource and climate enthusiasts to explore and study.
Year Completed |
1952 |
Dam Length |
1290 |
Dam Height |
12 |
River Or Stream |
TR-CABALLO CREEK |
Primary Dam Type |
Earth |
Surface Area |
15 |
Hydraulic Height |
12 |
Nid Storage |
72 |
Structural Height |
12 |
Outlet Gates |
None - 1 |
Hazard Potential |
Not Available |
Foundations |
Unlisted/Unknown |
Nid Height |
12 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Nueces Rv Nr Tilden
|
0cfs |
Frio Rv At Tilden
|
0cfs |
San Miguel Ck Nr Tilden
|
0cfs |
San Casimiro Ck Nr Freer
|
0cfs |
Choke Canyon Res Owc Nr Three Rivers
|
33cfs |
Nueces Rv At Cotulla
|
0cfs |
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.
Llano Grande Tank Dam