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Sewage treatment plant, major discharger, O'fallon, Missouri. NPDES permit MO0028720, in force until Sep 30, 2031. Last 12 months: no values over a limit. Source: EPA ECHO, Oct 22, 2026.
| Parameter | Statistic | Limit | Months | Outfall |
|---|---|---|---|---|
| pH | minimum | ≥ 6 SU | all year | 001 |
| pH | maximum | ≤ 9 SU | all year | 001 |
| Solids, total suspended | weekly average | ≤ 45 mg/L | all year | 001 |
| Solids, total suspended | monthly average | ≤ 30 mg/L | all year | 001 |
| Oil and grease [soxhlet extr.] tot. | daily maximum | ≤ 15 mg/L | all year | 001 |
| Oil and grease [soxhlet extr.] tot. | monthly average | ≤ 10 mg/L | all year | 001 |
| Nitrogen, total [as N] | daily maximum | report only (mg/L) | all year | 001 |
| Nitrogen, total [as N] | monthly average | report only (mg/L) | all year | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | report only (mg/L) | all year | 001 |
| Nitrogen, ammonia total [as N] | monthly average | report only (mg/L) | all year | 001 |
| Nitrogen, Kjeldahl, total [as N] | daily maximum | report only (mg/L) | all year | 001 |
| Nitrogen, Kjeldahl, total [as N] | monthly average | report only (mg/L) | all year | 001 |
| Nitrite + Nitrate total [as N] | daily maximum | report only (mg/L) | all year | 001 |
| Nitrite + Nitrate total [as N] | monthly average | report only (mg/L) | all year | 001 |
| Phosphorus, total [as P] | daily maximum | report only (mg/L) | all year | 001 |
| Phosphorus, total [as P] | monthly average | report only (mg/L) | all year | 001 |
| Flow, in conduit or thru treatment plant | daily maximum | report only (MGD) | all year | 001 |
| Flow, in conduit or thru treatment plant | monthly average | report only (MGD) | all year | 001 |
| BOD, 5 day carbonaceous, % rmvl, wet | monthly average minimum | ≥ 85 % | all year | 001 |
| E. coli | 7-day geometric mean | ≤ 630 #/100mL | Apr–Oct | 001 |
| E. coli | 30-day geometric mean | ≤ 126 #/100mL | Apr–Oct | 001 |
| Toxicity [acute], Ceriodaphnia dubia | daily maximum | report only (toxic) | all year | 001 |
| Toxicity [acute], Pimephales promelas [Fathead Minnow] | daily maximum | report only (toxic) | all year | 001 |
| BOD, carbonaceous [20 day, 20 C] | weekly average | ≤ 40 mg/L | all year | 001 |
| BOD, carbonaceous [20 day, 20 C] | monthly average | ≤ 25 mg/L | all year | 001 |
| Solids, suspended percent removal | monthly average minimum | ≥ 85 % | all year | 001 |
| Flow, total | monthly total | report only (MGD) | all year | 001 |
| pH | minimum | ≥ 6.5 SU | all year | 002 |
| pH | maximum | ≤ 9 SU | all year | 002 |
| Solids, total suspended | weekly average | ≤ 45 mg/L | all year | 002 |
| Oil and grease [soxhlet extr.] tot. | daily maximum | ≤ 15 mg/L | all year | 002 |
| Nitrogen, total [as N] | daily maximum | report only (mg/L) | all year | 002 |
| Nitrogen, total [as N] | monthly average | report only (mg/L) | all year | 002 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 23.8 mg/L | all year | 002 |
| Nitrogen, Kjeldahl, total [as N] | daily maximum | report only (mg/L) | all year | 002 |
| Nitrogen, Kjeldahl, total [as N] | monthly average | report only (mg/L) | all year | 002 |
| Nitrite + Nitrate total [as N] | daily maximum | report only (mg/L) | all year | 002 |
| Nitrite + Nitrate total [as N] | monthly average | report only (mg/L) | all year | 002 |
| Phosphorus, total [as P] | daily maximum | report only (mg/L) | all year | 002 |
| Phosphorus, total [as P] | monthly average | report only (mg/L) | all year | 002 |
| Flow, in conduit or thru treatment plant | daily maximum | report only (MGD) | all year | 002 |
| Flow, in conduit or thru treatment plant | monthly average | report only (MGD) | all year | 002 |
| BOD, 5 day carbonaceous, % rmvl, wet | monthly average minimum | ≥ 85 % | all year | 002 |
| E. coli | weekly average | ≤ 630 #/100mL | Apr–Oct | 002 |
| BOD, carbonaceous [20 day, 20 C] | weekly average | ≤ 40 mg/L | all year | 002 |
| Solids, suspended percent removal | monthly average minimum | ≥ 85 % | all year | 002 |
| Flow, total | monthly total | report only (MGD) | all year | 002 |
| Solids, total suspended | monthly average | report only (mg/L) | all year | INF |
| Nitrogen, ammonia total [as N] | daily maximum | report only (mg/L) | all year | INF |
| Nitrogen, ammonia total [as N] | monthly average | report only (mg/L) | all year | INF |
| Nitrogen, Kjeldahl, total [as N] | daily maximum | report only (mg/L) | all year | INF |
| Nitrogen, Kjeldahl, total [as N] | monthly average | report only (mg/L) | all year | INF |
| Nitrite + Nitrate total [as N] | daily maximum | report only (mg/L) | all year | INF |
| Nitrite + Nitrate total [as N] | monthly average | report only (mg/L) | all year | INF |
| Phosphorus, total [as P] | daily maximum | report only (mg/L) | all year | INF |
| Phosphorus, total [as P] | monthly average | report only (mg/L) | all year | INF |
| BOD, carbonaceous [20 day, 20 C] | monthly average | report only (mg/L) | all year | INF |
Cited limits by parameter: Missouri's rules and the federal ones.
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On EPA ECHO: Facility report · DMR history
Your permit document is the final word. As JSON: /api/v1/permits/MO0028720 · MCP: https://passage-data.com/mcp