Upper San Marcos River Ws Nrcs Site 5 Dam Reservoir Report

Last Updated: December 5, 2025

Located on the Upper San Marcos River in Hays County, Texas, the NRCS Site 5 Dam stands as a testament to the collaborative efforts of the local government and the USDA NRCS in managing flood risk along the Purgatory Creek.


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Summary

Completed in 1989, this earth dam with a maximum height of 80 feet and a length of 2959 feet plays a crucial role in reducing the impact of flooding in the region, with a storage capacity of 7329 acre-feet.

With a drainage area of 14.41 square miles and a maximum discharge capacity of 50278 cubic feet per second, the dam is designed to mitigate flood events while maintaining a satisfactory condition assessment as of May 2018. The uncontrolled spillway, with a width of 305 feet, adds an extra layer of protection in times of high water levels. Despite its moderate risk rating, the NRCS Site 5 Dam continues to serve as a vital infrastructure for flood risk reduction in the area, showcasing the importance of proactive water resource management in the face of climate change challenges.

Years Modified

2000 - Other

Year Completed

1989

Dam Length

2959

Dam Height

71

River Or Stream

PURGATORY CREEK

Primary Dam Type

Earth

Surface Area

30

Hydraulic Height

71

Drainage Area

14.41

Nid Storage

7329

Structural Height

80

Outlet Gates

Uncontrolled - 2

Hazard Potential

Not Available

Foundations

Soil

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.