Clean Water Act discharge permit · NPDES MT0021920
CITY OF GREAT FALLS WWTP, Great Falls, MT: NPDES MT0021920 discharge permit, effluent exceedances, inspections, penalties
- Administratively continuedPermit status
- MajorDischarger class
- 32Pollutants under a numeric limit
- 3Pollutants with an effluent exceedance
CITY OF GREAT FALLS WWTP, held by CITY OF GREAT FALLS, holds NPDES permit MT0021920, which discharges to Missouri River. EPA’s file records it issued October 20, 2010 and expiring November 30, 2015. 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 | CITY OF GREAT FALLS WWTP |
|---|---|
| Permittee as filed | CITY OF GREAT FALLS |
| NPDES ID | MT0021920 |
| Permit status | Administratively continued (past its expiration date and still in force until reissued) |
| Permit type | Individual permit |
| Discharger class | Major discharger |
| Facility type | Publicly owned treatment works |
| Program | Publicly owned treatment works |
| Issued | October 20, 2010 |
| Expiration date | November 30, 2015 |
| Address | Great Falls, MT 59404 |
| Receiving water | MISSOURI RIVER |
| Receiving water impaired | 303(D) Listed |
| Subwatershed | Missouri River-Great Falls (HUC 100301021201) |
Cited to the EPA ICIS-NPDES permit file (ECHO download).
Effluent limits and exceedances
- 35Pollutants on file
- 32Under a numeric limit
- 6With a violation of any kind
- 3With 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 |
|---|---|---|---|---|---|
| Arsenic, total recoverable | 6 | 36 | 36 | April 30, 2018 | 141% over the limit |
| Nitrogen, ammonia total [as N] | 4 | 2 | 2 | December 31, 2018 | 96% over the limit |
| BOD, carbonaceous, percent removal | 0 | 1 | 1 | June 30, 2005 | 11% over the limit |
| Nitrogen, total [as N] | 4 | 2 | 0 | ||
| Toxicity [acute], Ceriodaphnia dubia | 0 | 2 | 0 | ||
| Toxicity [acute], Pimephales promelas [Fathead Minnow] | 0 | 1 | 0 | ||
| Solids, total suspended | 14 | 0 | 0 | ||
| BOD, 5-day, 20 deg. C | 10 | 0 | 0 | ||
| Copper, total recoverable | 6 | 0 | 0 | ||
| E. coli, MTEC-MF | 6 | 0 | 0 | ||
| Flow rate | 4 | 0 | 0 | ||
| Phosphorus, total [as P] | 4 | 0 | 0 | ||
| Selenium, total recoverable | 4 | 0 | 0 | ||
| Thallium, total recoverable | 4 | 0 | 0 | ||
| Chlorine, total residual | 3 | 0 | 0 | ||
| Temperature, water deg. centigrade | 2 | 0 | 0 | ||
| Oxygen, dissolved [DO] | 2 | 0 | 0 | ||
| pH | 2 | 0 | 0 | ||
| Oil and grease, hexane extr method | 2 | 0 | 0 | ||
| Nitrogen, Kjeldahl, total [as N] | 2 | 0 | 0 | ||
| Nitrite + Nitrate total [as N] | 2 | 0 | 0 | ||
| 1,2-Dichloroethane | 2 | 0 | 0 | ||
| Chloroform | 2 | 0 | 0 | ||
| Toluene | 2 | 0 | 0 | ||
| Di[2-ethylhexyl] phthalate [DEHP] | 2 | 0 | 0 | ||
| Pass/Fail Static Renewal 96Hr Acute Pimephales Promelas | 2 | 0 | 0 | ||
| Cyanide, total [as CN] | 1 | 0 | 0 | ||
| Bromodichloromethane, effluent | 1 | 0 | 0 | ||
| Phenols | 1 | 0 | 0 | ||
| Bromodichloromethane | 1 | 0 | 0 | ||
| Solids, total dissolved [TDS] | 1 | 0 | 0 | ||
| BOD, 5-day, percent removal | 1 | 0 | 0 | ||
| Solids, suspended percent removal | 1 | 0 | 0 | ||
| Oil and grease visual | 1 | 0 | 0 | ||
| Pass/Fail Static Renewal 48Hr Acute Ceriodaphnia dubia | 1 | 0 | 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
- 7Single-event violations
| Date | What EPA recorded | Agency |
|---|---|---|
| December 31, 2024 | PR: Failure to issue/reissue control mechanisms to at least 90% of SIU/CIUs w/in 6 months (Level II) | ST6 |
| April 9, 2024 | Monitoring Violations - Frequency of Sampling Violation | ST6 |
| April 9, 2024 | Monitoring Violations - Invalid/Unrepresentative Sample | ST6 |
| April 9, 2024 | Reporting Violations - Improper/ Incorrect Reporting | ST6 |
| February 15, 2022 | Monitoring Violations - Invalid/Unrepresentative Sample | ST6 |
| February 15, 2022 | Reporting Violations - Improper/ Incorrect Reporting | ST6 |
| February 15, 2022 | Monitoring Violations - Improper Analysis or Lab Error | ST6 |
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.
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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 MT0021920 there.
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Figures from EPA’s ICIS-NPDES download, loaded September 15, 2026.