Upper San Marcos River Ws Scs Site 1 Reservoir Report

Last Updated: December 5, 2025

Located in Hays, Texas, the Upper San Marcos River WS SCS Site 1 is a flood risk reduction structure designed by the USDA NRCS in 1983.


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Summary

This earth dam on Sink Creek stands at 80 feet tall and stretches 2905 feet in length, with a storage capacity of 18,399 acre-feet to mitigate potential flooding in the area. The dam's spillway, with a width of 354 feet, is uncontrolled, allowing for efficient water flow during high discharge events.

Maintained by the TCEQ, this dam is crucial for protecting the surrounding communities from flooding, with a satisfactory condition assessment as of May 2018. The structure's emergency action plan dates back to March 2012, ensuring timely response in case of emergencies. With a moderate risk assessment, the Upper San Marcos River WS SCS Site 1 serves as a vital asset for water resource and climate enthusiasts in the region, highlighting the importance of effective flood risk reduction measures in preserving the local environment and community well-being.

Year Completed

1983

Dam Length

2905

Dam Height

80

River Or Stream

SINK CREEK

Primary Dam Type

Earth

Surface Area

25

Hydraulic Height

80

Drainage Area

33.6

Nid Storage

18399

Structural Height

80

Outlet Gates

Slide (sluice gate) - 1, Uncontrolled - 2

Hazard Potential

Not Available

Foundations

Unlisted/Unknown

Nid Height

80
       
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.