Clean Water Act discharge permit · NPDES IL0029815
MASON CITY STP, Mason City, IL: NPDES IL0029815 discharge permit, effluent exceedances, inspections, penalties
- Administratively continuedPermit status
- MinorDischarger class
- 11Pollutants under a numeric limit
- 6Pollutants with an effluent exceedance
MASON CITY STP, held by MASON CITY, CITY OF, holds NPDES permit IL0029815, which discharges to Unnamed Trib To Salt Creek. EPA’s file records it issued June 27, 2018 and expiring June 30, 2023. The status and dates are as EPA’s permit file stood when Velarion loaded it (September 15, 2026); EPA’s free Detailed Facility Report on ECHO carries the permit’s current standing.
Identity
| Facility as filed | MASON CITY STP |
|---|---|
| Permittee as filed | MASON CITY, CITY OF |
| NPDES ID | IL0029815 |
| Permit status | Administratively continued (past its expiration date and still in force until reissued) |
| Permit type | Individual permit |
| Discharger class | Minor discharger |
| Facility type | Publicly owned treatment works |
| Program | Publicly owned treatment works |
| Issued | June 27, 2018 |
| Expiration date | June 30, 2023 |
| Address | Mason City, IL 62664 |
| Receiving water | UNNAMED TRIB TO SALT CREEK |
| Subwatershed | Mason City (HUC 071300090803) |
Cited to the EPA ICIS-NPDES permit file (ECHO download).
Effluent limits and exceedances
- 14Pollutants on file
- 11Under a numeric limit
- 14With a violation of any kind
- 6With an effluent exceedance
An effluent exceedance is a discharge monitoring report value over the permit’s numeric limit (EPA’s violation code E90). A violation of any kind also counts a report not filed. Each row is EPA’s own count for that pollutant.
| Pollutant or measure | Limits | Violations, any kind | Effluent exceedances | Latest exceedance | Largest exceedance, as filed |
|---|---|---|---|---|---|
| Coliform, fecal general | 3 | 62 | 57 | September 30, 2021 | 99,999% over the limit |
| Solids, total suspended | 7 | 30 | 23 | May 31, 2019 | 113% over the limit |
| BOD, carbonaceous [5 day, 20 C] | 4 | 26 | 22 | August 31, 2023 | 198% over the limit |
| Oxygen, dissolved [DO] | 5 | 9 | 7 | May 31, 2023 | 10% over the limit |
| pH | 4 | 12 | 4 | April 30, 2017 | |
| Chlorine, total residual | 2 | 5 | 2 | October 31, 2012 | 73% over the limit |
| Rainfall duration | 0 | 10 | 0 | ||
| Duration | 0 | 10 | 0 | ||
| Rainfall | 0 | 8 | 0 | ||
| Overflows | 1 | 7 | 0 | ||
| Flow, in conduit or thru treatment plant | 4 | 4 | 0 | ||
| BOD, 5-day, 20 deg. C | 3 | 3 | 0 | ||
| Nitrogen, ammonia total [as N] | 2 | 2 | 0 | ||
| Flow, total | 1 | 2 | 0 |
Cited to the EPA ICIS-NPDES limits and effluent violations files (ECHO download); up to 60 rows shown, most exceedances first.
Inspections, violations and enforcement
- 0Single-event violations
EPA’s single-event violation file, as loaded, holds no violation for NPDES IL0029815.
Velarion’s copy of EPA’s ICIS-NPDES files does not include the inspections, formal enforcement actions and informal enforcement actions files, so this page shows none of them. EPA’s free Detailed Facility Report on ECHO lists this permit’s inspections, enforcement actions and penalties.
Cited to the EPA ICIS-NPDES violation, inspection and enforcement files (ECHO download); up to 50 rows of each shown, newest first.
Watch this permit
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EPA publishes a free Detailed Facility Report for every permit on ECHO: its compliance status quarter by quarter, its inspections, and its enforcement actions and penalties. EPA also sends free notices of new inspections and enforcement actions through ECHO Notify; enter NPDES ID IL0029815 there.
Nearby on the register
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Figures from EPA’s ICIS-NPDES download, loaded September 15, 2026.