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Mchenry, City of

Sewage treatment plant, major discharger, Mchenry, Illinois. NPDES permit IL0066257 expired Jun 30, 2026; its limits still apply. Last 12 months: over a limit once (last April 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 25 days after each period: outfall 001 form 0 monthly (25 values), outfall INF form L monthly (4 values), outfall 001 form S twice a year
Last report on file
August 2026
Oct 2024 – Sep 2025
0 values over a limit, 0 required values missing, 0 of 26 reports late

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

Period endingParameterReportedLimitOver by
April 2026Nitrogen, ammonia total [as N], daily maximum2.55 mg/L≤ 2.2 mg/L16%

Limits in force (77)

ParameterStatisticLimitMonthsOutfall
Oxygen, dissolved [DO]monthly average minimum≥ 5.5 mg/LJan, Feb, Aug, Sep, Oct, Nov, Dec001
Oxygen, dissolved [DO]minimum weekly average≥ 6 mg/LMar–Jul001
Oxygen, dissolved [DO]minimum weekly average≥ 4 mg/LJan, Feb, Aug, Sep, Oct, Nov, Dec001
Oxygen, dissolved [DO]daily minimum≥ 5 mg/LMar–Jul001
Oxygen, dissolved [DO]daily minimum≥ 3.5 mg/LJan, Feb, Aug, Sep, Oct, Nov, Dec001
pHminimum≥ 6 SUall year001
pHmaximum≤ 9 SUall year001
Solids, total suspendedmonthly average≤ 25 mg/Lall year001
Solids, total suspendedweekly average≤ 45 mg/Lall year001
Solids, total suspendedmonthly average≤ 3336 lb/dall year001
Solids, total suspendedweekly average≤ 6005 lb/dall year001
Oil & Greasedaily maximumreport only (mg/L)all year001
Oil & Greasedaily maximumreport only (mg/L)all year001
Nitrogen, total [as N]monthly averagereport only (mg/L)all year001
Nitrogen, total [as N]daily maximumreport only (mg/L)all year001
Nitrogen, ammonia total [as N]monthly average≤ 1.5 mg/LMar, Apr, May, Sep, Oct001
Nitrogen, ammonia total [as N]monthly average≤ 1.5 mg/LJun–Aug001
Nitrogen, ammonia total [as N]daily maximum≤ 2.2 mg/LMar, Apr, May, Sep, Oct001
Nitrogen, ammonia total [as N]daily maximum≤ 3.2 mg/LJun–Aug001
Nitrogen, ammonia total [as N]daily maximum≤ 2.7 mg/LJan, Feb, Nov, Dec001
Nitrogen, ammonia total [as N]monthly average≤ 200 lb/dMar, Apr, May, Sep, Oct001
Nitrogen, ammonia total [as N]monthly average≤ 200 lb/dJun–Aug001
Nitrogen, ammonia total [as N]daily maximum≤ 294 lb/dMar, Apr, May, Sep, Oct001
Nitrogen, ammonia total [as N]daily maximum≤ 427 lb/dJun–Aug001
Nitrogen, ammonia total [as N]daily maximum≤ 360 lb/dJan, Feb, Nov, Dec001
Phosphorus, total [as P]monthly average≤ 1 mg/Lall year001
Phosphorus, total [as P]monthly average≤ 133 lb/dall year001
Cyanide, total [as CN]daily maximumreport only (ug/L)all year001
Cyanide, total [as CN]daily maximumreport only (ug/L)all year001
Cyanide, free [amenable to chlorination]daily maximumreport only (ug/L)all year001
Cyanide, free [amenable to chlorination]daily maximumreport only (ug/L)all year001
Fluoride, total [as F]daily maximumreport only (mg/L)all year001
Fluoride, total [as F]daily maximumreport only (mg/L)all year001
Arsenic, total [as As]daily maximumreport only (mg/L)all year001
Arsenic, total [as As]daily maximumreport only (mg/L)all year001
Barium, total [as Ba]daily maximumreport only (mg/L)all year001
Barium, total [as Ba]daily maximumreport only (mg/L)all year001
Cadmium, total [as Cd]daily maximumreport only (mg/L)all year001
Cadmium, total [as Cd]daily maximumreport only (mg/L)all year001
Chromium, hexavalent [as Cr]daily maximumreport only (mg/L)all year001
Chromium, hexavalent [as Cr]daily maximumreport only (mg/L)all year001
Chromium, total [as Cr]daily maximumreport only (mg/L)all year001
Chromium, total [as Cr]daily maximumreport only (mg/L)all year001
Copper, total [as Cu]daily maximumreport only (mg/L)all year001
Copper, total [as Cu]daily maximumreport only (mg/L)all year001
Iron, total [as Fe]daily maximumreport only (mg/L)all year001
Iron, total [as Fe]daily maximumreport only (mg/L)all year001
Iron, dissolved [as Fe]daily maximumreport only (mg/L)all year001
Iron, dissolved [as Fe]daily maximumreport only (mg/L)all year001
Lead, total [as Pb]daily maximumreport only (mg/L)all year001
Lead, total [as Pb]daily maximumreport only (mg/L)all year001
Manganese, total [as Mn]daily maximumreport only (mg/L)all year001
Manganese, total [as Mn]daily maximumreport only (mg/L)all year001
Nickel, total [as Ni]daily maximumreport only (mg/L)all year001
Nickel, total [as Ni]daily maximumreport only (mg/L)all year001
Silver, total [as Ag]daily maximumreport only (mg/L)all year001
Silver, total [as Ag]daily maximumreport only (mg/L)all year001
Zinc, total [as Zn]daily maximumreport only (mg/L)all year001
Zinc, total [as Zn]daily maximumreport only (mg/L)all year001
Selenium, total [as Se]daily maximumreport only (mg/L)all year001
Selenium, total [as Se]daily maximumreport only (mg/L)all year001
Phenolics, total recoverabledaily maximumreport only (mg/L)all year001
Phenolics, total recoverabledaily maximumreport only (mg/L)all year001
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year001
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year001
Chlorine, total residualdaily maximum≤ .038 mg/Lall year001
Mercury, total [as Hg]daily maximumreport only (ng/L)all year001
Mercury, total [as Hg]daily maximumreport only (ng/L)all year001
Coliform, fecal generaldaily maximum≤ 400 #/100mLall year001
BOD, carbonaceous [5 day, 20 C]monthly average≤ 20 mg/Lall year001
BOD, carbonaceous [5 day, 20 C]weekly average≤ 40 mg/Lall year001
BOD, carbonaceous [5 day, 20 C]monthly average≤ 2669 lb/dall year001
BOD, carbonaceous [5 day, 20 C]weekly average≤ 5338 lb/dall year001
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all yearINF
Solids, total suspendedmonthly averagereport only (mg/L)all yearINF
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all yearINF
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all yearINF

How strict are these limits?

Cited limits by parameter: Illinois'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/IL0066257 · MCP: https://passage-data.com/mcp