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City of St. Charles

Sewage treatment plant, major discharger, St. Charles, Missouri. NPDES permit MO0058343 expired Jun 30, 2025; its limits still apply. Last 12 months: over a limit 2 times (last January 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: outfall 001 form M monthly (20 values), outfall 001 form WA yearly (2 values), outfall INF form IM monthly (12 values)
Last report on file
September 2026
Oct 2024 – Sep 2025
0 values over a limit, 0 required values missing, 1 of 25 reports late

Last 12 months (Oct 1, 2025 – Sep 30, 2026)

Period endingParameterReportedLimitOver by
January 2026BOD, 5-day, 20 deg. C, monthly average30.99≤ 30 mg/L3%
January 2026BOD, 5-day, percent removal, monthly average minimum81.85≥ 85 %21%

Limits in force (34)

ParameterStatisticLimitMonthsOutfall
BOD, 5-day, 20 deg. Cweekly average≤ 45 mg/Lall year001
BOD, 5-day, 20 deg. Cmonthly average≤ 30 mg/Lall year001
pHminimum≥ 6 SUall year001
pHmaximum≤ 9 SUall year001
Solids, total suspendedweekly average≤ 45 mg/Lall year001
Solids, total suspendedmonthly average≤ 30 mg/Lall year001
Oil and grease [soxhlet extr.] tot.daily maximum≤ 15 mg/Lall year001
Oil and grease [soxhlet extr.] tot.monthly average≤ 10 mg/Lall year001
Nitrogen, ammonia total [as N]daily maximum≤ 37.6 mg/Lall year001
Nitrogen, ammonia total [as N]monthly average≤ 37.6 mg/Lall year001
Nitrogen, Kjeldahl, total [as N]daily maximumreport only (mg/L)all year001
Nitrogen, Kjeldahl, total [as N]monthly averagereport only (mg/L)all year001
Nitrite + Nitrate total [as N]daily maximumreport only (mg/L)all year001
Nitrite + Nitrate total [as N]monthly averagereport only (mg/L)all year001
Phosphorus, total [as P]daily maximumreport only (mg/L)all year001
Phosphorus, total [as P]monthly averagereport only (mg/L)all year001
E. coli7-day geometric mean≤ 630 #/100mLApr–Oct001
E. coli30-day geometric mean≤ 126 #/100mLApr–Oct001
Toxicity [acute], Ceriodaphnia dubiadaily maximumreport only (toxic)all year001
Toxicity [acute], Pimephales promelas [Fathead Minnow]daily maximumreport only (toxic)all year001
BOD, 5-day, percent removalmonthly average minimum≥ 85 %all year001
Solids, suspended percent removalmonthly average minimum≥ 85 %all year001
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all yearINF
Solids, total suspendedmonthly averagereport only (mg/L)all yearINF
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)all yearINF
Nitrogen, ammonia total [as N]monthly averagereport only (mg/L)all yearINF
Nitrogen, Kjeldahl, total [as N]daily maximumreport only (mg/L)all yearINF
Nitrogen, Kjeldahl, total [as N]monthly averagereport only (mg/L)all yearINF
Nitrite + Nitrate total [as N]daily maximumreport only (mg/L)all yearINF
Nitrite + Nitrate total [as N]monthly averagereport only (mg/L)all yearINF
Phosphorus, total [as P]daily maximumreport only (mg/L)all yearINF
Phosphorus, total [as P]monthly averagereport only (mg/L)all yearINF
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all yearINF
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all yearINF

How strict are these limits?

Cited limits by parameter: Missouri's rules and the federal ones.

Check this month's numbers Email me before each report is due

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On EPA ECHO: Facility report · DMR history

Your permit document is the final word. As JSON: /api/v1/permits/MO0058343 · MCP: https://passage-data.com/mcp