Tiller Lake Dam Reservoir Report

Last Updated: December 6, 2025

Tiller Lake Dam, located in Webb County, Texas, is a privately owned earth dam built in 1974 on TR-Velenzuela Creek.


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Summary

Standing at a height of 10 feet and stretching 1200 feet in length, the dam provides a storage capacity of 104 acre-feet for its primary purpose. Despite being a non-regulated structure, Tiller Lake Dam has undergone state permitting and inspection processes, ensuring its safety and compliance with standards.

With a normal storage capacity of 28 acre-feet, Tiller Lake Dam serves as a vital resource for water management in the region. The dam, with its buttress core type and unlisted foundation, plays a crucial role in managing the water resources of the area. Even though it does not have a spillway, the dam features one outlet gate for water release when necessary, showcasing its functionality in maintaining water levels and mitigating potential flood risks.

Although Tiller Lake Dam has a high risk assessment rating, its condition is currently not rated, and it lacks an Emergency Action Plan (EAP). Despite these limitations, the dam remains a key structure for water resource management in the region, highlighting the importance of regular maintenance and monitoring to ensure its continued effectiveness in safeguarding the local community and environment.

Year Completed

1974

Dam Length

1200

Dam Height

10

River Or Stream

TR-VELENZUELA CREEK

Primary Dam Type

Earth

Surface Area

10

Hydraulic Height

10

Nid Storage

104

Structural Height

10

Outlet Gates

None - 1

Hazard Potential

Not Available

Foundations

Unlisted/Unknown

Nid Height

10
       
Seasonal Comparison

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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.