Brenni Lake Dam Reservoir Report

Last Updated: December 5, 2025

Brenni Lake Dam, also known as Mertz Dam, is a privately-owned structure located in Williamson County, Texas.


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Summary

Built in 1974 by the USDA NRCS, this earth dam stands at a height of 29 feet and spans 586 feet in length, with a primary purpose of providing fire protection, stock, and small fish pond. The dam has a storage capacity of 72 acre-feet, with a normal storage level of 59 acre-feet, and covers a surface area of 24 acres.

Managed by the Texas Commission on Environmental Quality (TCEQ), Brenni Lake Dam is regulated, permitted, inspected, and enforced by the state. Despite being rated as high risk due to its hazard potential, the condition of the dam is currently not rated, and it lacks an emergency action plan. With no spillway and a lack of drainage area, the dam poses potential risks that are being closely monitored by regulatory agencies to ensure public safety and environmental protection in the surrounding area.

Water resource and climate enthusiasts can appreciate Brenni Lake Dam for its role in providing essential services like fire protection, recreation, and stock water supply. While the dam's risk potential is a concern, ongoing oversight and regulation by the state demonstrate a commitment to maintaining the dam's integrity and safeguarding the surrounding community and ecosystem. As a key feature in the watershed of TR-LONG BRANCH, this dam serves as a reminder of the importance of sustainable water resource management in the face of changing climate conditions.

Year Completed

1974

Dam Length

586

Dam Height

29

River Or Stream

TR-LONG BRANCH

Primary Dam Type

Earth

Surface Area

24

Hydraulic Height

29

Nid Storage

72

Structural Height

29

Outlet Gates

None - 1

Hazard Potential

Not Available

Foundations

Unlisted/Unknown

Nid Height

29
       
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.