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PWSD No. 2 of St. Charles County

Sewage treatment plant, Wentzville, Missouri. NPDES permit MO0057801 expired Mar 31, 2025; its limits still apply. Last 12 months: no values over a limit. Source: EPA ECHO, Oct 22, 2026.

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

Limits in force (44)

ParameterStatisticLimitMonthsOutfall
Oxygen, dissolved [DO]daily minimumreport only (mg/L)Apr–Oct001
Oxygen, dissolved [DO]monthly average minimumreport only (mg/L)Apr–Oct001
BOD, 5-day, 20 deg. Cweekly average≤ 25 mg/Lall year001
BOD, 5-day, 20 deg. Cmonthly average≤ 25 mg/Lall year001
pHminimum≥ 6.5 SUall year001
pHmaximum≤ 9 SUall year001
Alkalinity, total [as CaCO3]daily maximumreport only (mg/L)all year001
Alkalinity, total [as CaCO3]monthly averagereport only (mg/L)all year001
Solids, total suspendedweekly average≤ 25 mg/Lall year001
Solids, total suspendedmonthly average≤ 25 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≤ 8.4 mg/LSep001
Nitrogen, ammonia total [as N]daily maximum≤ 12.1 mg/LMay001
Nitrogen, ammonia total [as N]daily maximum≤ 10.1 mg/LMar, Dec001
Nitrogen, ammonia total [as N]daily maximum≤ 8.4 mg/LApr001
Nitrogen, ammonia total [as N]daily maximum≤ 12.1 mg/LJan, Feb001
Nitrogen, ammonia total [as N]daily maximum≤ 10.1 mg/LJun001
Nitrogen, ammonia total [as N]daily maximum≤ 8.4 mg/LNov001
Nitrogen, ammonia total [as N]daily maximum≤ 8.4 mg/LJul, Aug001
Nitrogen, ammonia total [as N]daily maximum≤ 8.4 mg/LOct001
Nitrogen, ammonia total [as N]monthly average≤ 1.2 mg/LSep001
Nitrogen, ammonia total [as N]monthly average≤ 2.1 mg/LMay001
Nitrogen, ammonia total [as N]monthly average≤ 2.7 mg/LMar, Dec001
Nitrogen, ammonia total [as N]monthly average≤ 2.1 mg/LApr001
Nitrogen, ammonia total [as N]monthly average≤ 3.1 mg/LJan, Feb001
Nitrogen, ammonia total [as N]monthly average≤ 1.3 mg/LJun001
Nitrogen, ammonia total [as N]monthly average≤ 2.4 mg/LNov001
Nitrogen, ammonia total [as N]monthly average≤ .9 mg/LJul, Aug001
Nitrogen, ammonia total [as N]monthly average≤ 1.8 mg/LOct001
Hardness, total [as CaCO3]daily maximumreport only (mg/L)all year001
Hardness, total [as CaCO3]monthly averagereport only (mg/L)all year001
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year001
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year001
Chlorine, total residualdaily maximum≤ 19 ug/LApr–Oct001
Chlorine, total residualmonthly average≤ 7 ug/LApr–Oct001
E. coli7-day geometric mean≤ 1030 #/100mLApr–Oct001
E. coli30-day geometric mean≤ 206 #/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

How strict are these limits?

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/MO0057801 · MCP: https://passage-data.com/mcp