Granger Dam Reservoir Report

Last Updated: December 5, 2025

Granger Dam, also known as Granger Lake, is a Federal-owned water supply dam located in Laneport, Williamson County, Texas.


°F

°F

mph

Wind

%

Humidity

Summary

Completed in 1979, this Earth dam serves multiple purposes including fish and wildlife pond, flood risk reduction, recreation, and of course, water supply for the region. With a height of 115 feet and a storage capacity of 650,000 acre-feet, the dam poses a high hazard potential due to its location on the San Gabriel River.

Despite the risks associated with the dam, USACE Fort Worth District has implemented various risk management measures to ensure the safety and stability of Granger Dam. Regular inspections, surveillance, and monitoring are conducted to detect potential concerns, especially during high water levels. Additionally, the district works closely with local emergency managers to develop and update evacuation plans, conduct emergency exercises, and communicate risks to stakeholders. Although the dam reduces flooding risk downstream, the possibility of a breach could have severe consequences for nearby rural communities and cities, emphasizing the importance of continued vigilance and proactive risk mitigation efforts.

Year Completed

1979

Dam Length

15240

Dam Height

115

River Or Stream

SAN GABRIEL RIVER

Primary Dam Type

Earth

Surface Area

4400

Hydraulic Height

114

Drainage Area

475

Nid Storage

650000

Structural Height

115

Outlet Gates

Uncontrolled - 0

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

115
       
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.