San Marcos WWTP
San Marcos, TX · Hays County · Publicly Owned Treatment Works
- Average flow
- 6.1 MGD
- Design flow
- 9 MGD
- NPDES permit
- TX0047945
- Effective
- Permit expires
- January 2030
- Population served
- 52,088
- CWNS 2022
San Marcos WWTP is a publicly owned wastewater treatment works in San Marcos, Hays County, Texas treating an average of 6.1 million gallons per day against a permitted design capacity of 9 MGD, serving about 52,088 residents. Treatment on site includes clarifiers, carrousels / oxidation ditches, biogas silos, biogas balloons. It discharges under NPDES permit TX0047945 (effective), which expires in January 2030, with 87 recorded violations in the last three years.
Treatment technology
Treatment structures identified at this facility. Exact unit counts are available in Klarifi.
Clarifiers
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Carrousels / oxidation ditches
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Biogas silos
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Biogas balloons
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Compliance snapshot (last 3 years)
- Total violations
- 87
- Effluent violations
- 87
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
19 verified contacts for San Marcos WWTP, with validated emails and direct phone numbers.
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Names, validated emails and direct phone numbers for decision-makers at San Marcos WWTP, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Texas
Kyle · 9 mi away
4.34 MGD
City Of New Braunfels · 10 mi away
0.01 MGD
New Braunfels · 14 mi away
1.4 MGD
Buda · 16 mi away
0.89 MGD
Buda · 16 mi away
1.29 MGD
New Braunfels · 16 mi away
2.1 MGD
New Braunfels · 16 mi away
3.26 MGD
Seguin · 17 mi away
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San Marcos WWTP: frequently asked questions
Sources and methodology
Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.
Data refreshed September 11, 2026; facility record last updated April 7, 2025.