Rio Vista Dam Reservoir Report

Last Updated: December 5, 2025

Rio Vista Dam, located on the San Marcos River in Hays County, Texas, was completed in 1904 and serves primarily for recreation purposes.


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Summary

The dam stands at a height of 8 feet and has a length of 100 feet, with a storage capacity of 61 acre-feet. Despite its age, the dam remains in good condition with a hazard potential labeled as "Not Available" and a risk assessment rating of "High (2)".

The dam, constructed of concrete with a buttress core type, is under state regulation and inspection by the Texas Commission on Environmental Quality (TCEQ). While it does not have a spillway, the dam features a single outlet gate. The surrounding area offers a surface area of 16.5 acres for recreational activities, making it a popular spot for water resource and climate enthusiasts to enjoy nature and explore the scenic beauty of the San Marcos River.

In 2006, the dam underwent modifications, and its Emergency Action Plan (EAP) was last revised in 2011. With a risk management evaluation of "High (2)", Rio Vista Dam continues to be a significant structure for water management in the region, providing both recreational opportunities and vital support for the local environment.

Years Modified

2006 - Other

Year Completed

1904

Dam Length

100

Dam Height

8

River Or Stream

SAN MARCOS RIVER

Primary Dam Type

Concrete

Surface Area

16.5

Hydraulic Height

8

Nid Storage

61

Structural Height

8

Outlet Gates

None - 1

Hazard Potential

Not Available

Foundations

Unlisted/Unknown

Nid Height

8
       
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.