Mason City Stp, City Of
Mason City, IL · Mason County · Publicly Owned Treatment Works
- Average flow
- 0.26 MGD
- Design flow
- —
- NPDES permit
- ILL029815
- Effective
- Permit expires
- December 2030
- Population served
- 3,136
- CWNS 2022
Mason City Stp, City Of is a publicly owned wastewater treatment works in Mason City, Mason County, Illinois treating an average of 0.26 million gallons per day, serving about 3,136 residents. Treatment on site includes clarifiers, aerated lagoons, uncovered lagoons. It discharges under NPDES permit ILL029815 (effective), which expires in December 2030, with 0 recorded violations in the last three years.
Treatment technology
Treatment structures identified at this facility. Exact unit counts are available in Klarifi.
Compliance snapshot (last 3 years)
- Total violations
- 0
- Effluent violations
- 0
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
2 verified contacts for Mason City Stp, City Of, with validated emails and direct phone numbers.
Unlock 2 verified contacts
Names, validated emails and direct phone numbers for decision-makers at Mason City Stp, City Of, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Illinois
Easton · 9 mi away
—
San Jose · 10 mi away
0.03 MGD
Green Valley · 13 mi away
0.02 MGD
Petersburg · 13 mi away
0.14 MGD
Delavan · 15 mi away
0.07 MGD
Athens · 16 mi away
0.11 MGD
Manito · 18 mi away
0.06 MGD
Williamsville · 18 mi away
0.12 MGD
Mason City Stp, City Of: 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 November 6, 2025.