Upper San Marcos River WS SCS Site 1

SINK CREEK· Hays, Texas· Built 1983· Earth· 80 ft tall
High Hazard Flood Risk Reduction Local Government

Key Takeaway

Upper San Marcos River WS SCS Site 1 is classified as high hazard in Texas. It was completed in 1983 and is 43 years old. Its primary use is flood risk reduction. High hazard means loss of life is likely if the dam fails — it does not indicate the dam's current condition. Learn more.

Physical Details

Dam Height 80 ft (taller than 98.6% in TX)
Dam Length2,905 ft
Dam TypeEarth
Max Storage18.4K acre-ft
Normal Storage304 acre-ft
Surface Area25 acres
Drainage Area34 sq mi
Max Discharge76,927 cfs
Year Completed1983 (43 years old)
NID IDTX05945

Safety Information

High Hazard

Loss of human life is likely if the dam fails.

Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?

Emergency Action Plan: Yes
Last Inspection: October 13, 2020
State Regulated: Yes
Regulatory Agency: TCEQ

Ownership

CITY OF SAN MARCOS;HAYS COUNTY;HAYS COUNTY SWCD;UPPER SAN MARCOS WS RECL FCD

Local Government

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Upper San Marcos River WS SCS Site 1?

Upper San Marcos River WS SCS Site 1 is classified as High Hazard. Loss of human life is likely if the dam fails. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Upper San Marcos River WS SCS Site 1?

Upper San Marcos River WS SCS Site 1 is owned by CITY OF SAN MARCOS;HAYS COUNTY;HAYS COUNTY SWCD;UPPER SAN MARCOS WS RECL FCD (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Upper San Marcos River WS SCS Site 1 built?

Upper San Marcos River WS SCS Site 1 was completed in 1983, making it 43 years old. Many U.S. dams were built between the 1930s and 1970s during a period of major infrastructure investment.

What is the primary purpose of Upper San Marcos River WS SCS Site 1?

Upper San Marcos River WS SCS Site 1 serves the following purposes: Flood Risk Reduction. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Upper San Marcos River WS SCS Site 1?

Upper San Marcos River WS SCS Site 1 has a dam height of 80 ft. Dam height is measured from the natural streambed at the downstream toe to the top of the dam, and may differ from the visible height.

When was Upper San Marcos River WS SCS Site 1 last inspected?

Upper San Marcos River WS SCS Site 1 was last inspected on October 13, 2020. Inspection dates indicate when a formal review occurred, not the results of that inspection.

Data from the National Inventory of Dams (NID) maintained by the US Army Corps of Engineers. Dam conditions may have changed since the last update. This site is not affiliated with USACE. Do not use for emergency planning — contact your local dam safety program.