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Sewage treatment plant, St. Charles, Missouri. NPDES permit MO0129763 expired Jun 30, 2025; its limits still apply. Last 12 months: over a limit 2 times (last March 2026). Source: EPA ECHO, Oct 22, 2026.
| Period ending | Parameter | Reported | Limit | Over by |
|---|---|---|---|---|
| March 2026 | Nitrogen, ammonia total [as N], daily maximum | 11.4 | ≤ 5.5 mg/L | 107% |
| March 2026 | Nitrogen, ammonia total [as N], monthly average | 1.8 | ≤ 1.3 mg/L | 38% |
| Parameter | Statistic | Limit | Months | Outfall |
|---|---|---|---|---|
| BOD, 5-day, 20 deg. C | daily maximum | ≤ 10 mg/L | all year | 001 |
| BOD, 5-day, 20 deg. C | monthly average | ≤ 6.7 mg/L | all year | 001 |
| pH | minimum | ≥ 6 SU | all year | 001 |
| pH | maximum | ≤ 9 SU | all year | 001 |
| Solids, total suspended | daily maximum | ≤ 10 mg/L | all year | 001 |
| Solids, total suspended | monthly average | ≤ 6.7 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, ammonia total [as N] | daily maximum | ≤ 5.5 mg/L | Jan, Feb, Mar, Apr, Nov, Dec | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | ≤ 4.3 mg/L | May–Dec | 001 |
| Nitrogen, ammonia total [as N] | monthly average | ≤ 1.3 mg/L | Jan, Feb, Mar, Apr, Nov, Dec | 001 |
| Nitrogen, ammonia total [as N] | monthly average | ≤ 1.2 mg/L | May–Dec | 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 |
| E. coli | 7-day geometric mean | ≤ 1030 #/100mL | Apr–Dec | 001 |
| E. coli | 30-day geometric mean | ≤ 206 #/100mL | Apr–Dec | 001 |
| BOD, 5-day, percent removal | monthly average minimum | ≥ 85 % | all year | 001 |
| Solids, suspended percent removal | monthly average minimum | ≥ 85 % | all year | 001 |
| BOD, 5-day, 20 deg. C | monthly average | report only (mg/L) | all year | INF |
| Solids, total suspended | 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/MO0129763 · MCP: https://passage-data.com/mcp