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Illinois American Water Company

Sewerage Systems, major discharger, Lockport, Illinois. NPDES permit IL0055981 expired Oct 31, 2025; its limits still apply. Last 12 months: over a limit once (last February 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 25 days after each period: outfall 001 form 0 monthly (15 values), outfall A01 form 0 monthly (5 values), outfall B01 form 0 monthly (26 values), outfall INF form L monthly (4 values), outfall B01 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 50 reports late

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

Period endingParameterReportedLimitOver by
February 2026Phosphorus, total [as P], monthly average1.31 mg/L≤ 1 mg/L31%

Limits in force (106)

ParameterStatisticLimitMonthsOutfall
Oxygen, dissolved [DO]monthly average minimumreport only (mg/L)all year001
Oxygen, dissolved [DO]minimum weekly averagereport only (mg/L)all year001
Oxygen, dissolved [DO]daily minimumreport only (mg/L)all year001
BOD, 5-day, 20 deg. Cmonthly average≤ 30 mg/Lall year001
BOD, 5-day, 20 deg. Cweekly average≤ 45 mg/Lall year001
pHminimum≥ 6 SUall year001
pHmaximum≤ 9 SUall year001
Solids, total suspendedmonthly average≤ 30 mg/Lall year001
Solids, total suspendedweekly average≤ 45 mg/Lall year001
Nitrogen, ammonia total [as N]monthly averagereport only (mg/L)all year001
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)all year001
Phosphorus, total [as P]daily maximumreport only (mg/L)all year001
Chlorine, total residualmonthly average≤ .75 mg/Lall year001
Coliform, fecal generaldaily maximum≤ 400 #/100mLall year001
Flow, totalmonthly totalreport only (MGD)all year001
BOD, 5-day, 20 deg. Cdaily maximumreport only (mg/L)all yearA01
Solids, total suspendeddaily maximumreport only (mg/L)all yearA01
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)all yearA01
Phosphorus, total [as P]daily maximumreport only (mg/L)all yearA01
Flow, totalmonthly totalreport only (Mgal/mo)all yearA01
Oxygen, dissolved [DO]monthly average minimum≥ 5.5 mg/LJan, Feb, Aug, Sep, Oct, Nov, DecB01
Oxygen, dissolved [DO]minimum weekly average≥ 6 mg/LMar–JulB01
Oxygen, dissolved [DO]minimum weekly average≥ 4 mg/LJan, Feb, Aug, Sep, Oct, Nov, DecB01
Oxygen, dissolved [DO]daily minimum≥ 5 mg/LMar–JulB01
Oxygen, dissolved [DO]daily minimum≥ 3.5 mg/LJan, Feb, Aug, Sep, Oct, Nov, DecB01
pHminimum≥ 6 SUall yearB01
pHmaximum≤ 9 SUall yearB01
Solids, total suspendedannual average≤ 250 lb/dall yearB01
Solids, total suspendedmonthly average≤ 12 mg/Lall yearB01
Solids, total suspendeddaily maximum≤ 24 mg/Lall yearB01
Solids, total suspendedmonthly average≤ 375 lb/dall yearB01
Solids, total suspendeddaily maximum≤ 751 lb/dall yearB01
Oil & Greasedaily maximumreport only (mg/L)all yearB01
Oil & Greasedaily maximumreport only (mg/L)all yearB01
Nitrogen, total [as N]daily maximumreport only (mg/L)all yearB01
Nitrogen, ammonia total [as N]weekly average≤ .8 mg/LJun–AugB01
Nitrogen, ammonia total [as N]weekly average≤ 25 lb/dJun–AugB01
Nitrogen, ammonia total [as N]monthly average≤ .3 mg/LJun–AugB01
Nitrogen, ammonia total [as N]monthly average≤ 2.2 mg/LJan, Feb, Nov, DecB01
Nitrogen, ammonia total [as N]monthly average≤ 1.4 mg/LApr, May, Sep, OctB01
Nitrogen, ammonia total [as N]monthly average≤ 1.4 mg/LMarB01
Nitrogen, ammonia total [as N]daily maximum≤ 1.8 mg/LJun–AugB01
Nitrogen, ammonia total [as N]daily maximum≤ 3.2 mg/LJan, Feb, Nov, DecB01
Nitrogen, ammonia total [as N]daily maximum≤ 3 mg/LApr, May, Sep, OctB01
Nitrogen, ammonia total [as N]daily maximum≤ 3.2 mg/LMarB01
Nitrogen, ammonia total [as N]monthly average≤ 9.4 lb/dJun–AugB01
Nitrogen, ammonia total [as N]monthly average≤ 69 lb/dJan, Feb, Nov, DecB01
Nitrogen, ammonia total [as N]monthly average≤ 44 lb/dApr, May, Sep, OctB01
Nitrogen, ammonia total [as N]monthly average≤ 44 lb/dMarB01
Nitrogen, ammonia total [as N]daily maximum≤ 56 lb/dJun–AugB01
Nitrogen, ammonia total [as N]daily maximum≤ 100 lb/dJan, Feb, Nov, DecB01
Nitrogen, ammonia total [as N]daily maximum≤ 94 lb/dApr, May, Sep, OctB01
Nitrogen, ammonia total [as N]daily maximum≤ 100 lb/dMarB01
Phosphorus, total [as P]monthly average≤ 1 mg/Lall yearB01
Phosphorus, total [as P]monthly average≤ 31 lb/dall yearB01
Cyanide, total [as CN]daily maximumreport only (ug/L)all yearB01
Cyanide, total [as CN]daily maximumreport only (ug/L)all yearB01
Cyanide, free [amenable to chlorination]daily maximumreport only (ug/L)all yearB01
Cyanide, free [amenable to chlorination]daily maximumreport only (ug/L)all yearB01
Fluoride, total [as F]daily maximumreport only (mg/L)all yearB01
Fluoride, total [as F]daily maximumreport only (mg/L)all yearB01
Arsenic, total [as As]daily maximumreport only (mg/L)all yearB01
Arsenic, total [as As]daily maximumreport only (mg/L)all yearB01
Barium, total [as Ba]daily maximumreport only (mg/L)all yearB01
Barium, total [as Ba]daily maximumreport only (mg/L)all yearB01
Cadmium, total [as Cd]daily maximumreport only (mg/L)all yearB01
Cadmium, total [as Cd]daily maximumreport only (mg/L)all yearB01
Chromium, hexavalent [as Cr]daily maximumreport only (mg/L)all yearB01
Chromium, hexavalent [as Cr]daily maximumreport only (mg/L)all yearB01
Chromium, total [as Cr]daily maximumreport only (mg/L)all yearB01
Chromium, total [as Cr]daily maximumreport only (mg/L)all yearB01
Copper, total [as Cu]daily maximumreport only (mg/L)all yearB01
Copper, total [as Cu]daily maximumreport only (mg/L)all yearB01
Iron, total [as Fe]daily maximumreport only (mg/L)all yearB01
Iron, total [as Fe]daily maximumreport only (mg/L)all yearB01
Iron, dissolved [as Fe]daily maximumreport only (mg/L)all yearB01
Iron, dissolved [as Fe]daily maximumreport only (mg/L)all yearB01
Lead, total [as Pb]daily maximumreport only (mg/L)all yearB01
Lead, total [as Pb]daily maximumreport only (mg/L)all yearB01
Manganese, total [as Mn]daily maximumreport only (mg/L)all yearB01
Manganese, total [as Mn]daily maximumreport only (mg/L)all yearB01
Nickel, total [as Ni]daily maximumreport only (mg/L)all yearB01
Nickel, total [as Ni]daily maximumreport only (mg/L)all yearB01
Silver, total [as Ag]daily maximumreport only (mg/L)all yearB01
Silver, total [as Ag]daily maximumreport only (mg/L)all yearB01
Zinc, total [as Zn]daily maximumreport only (mg/L)all yearB01
Zinc, total [as Zn]daily maximumreport only (mg/L)all yearB01
Selenium, total [as Se]daily maximumreport only (mg/L)all yearB01
Selenium, total [as Se]daily maximumreport only (mg/L)all yearB01
Phenolics, total recoverabledaily maximumreport only (mg/L)all yearB01
Phenolics, total recoverabledaily maximumreport only (mg/L)all yearB01
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all yearB01
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all yearB01
Chlorine, total residualdaily maximum≤ .05 mg/Lall yearB01
Mercury, total [as Hg]daily maximumreport only (ng/L)all yearB01
Mercury, total [as Hg]daily maximumreport only (ng/L)all yearB01
Coliform, fecal generaldaily maximum≤ 400 #/100mLMay–OctB01
BOD, carbonaceous [5 day, 20 C]annual average≤ 206 lb/dall yearB01
BOD, carbonaceous [5 day, 20 C]monthly average≤ 10 mg/Lall yearB01
BOD, carbonaceous [5 day, 20 C]daily maximum≤ 20 mg/Lall yearB01
BOD, carbonaceous [5 day, 20 C]monthly average≤ 313 lb/dall yearB01
BOD, carbonaceous [5 day, 20 C]daily maximum≤ 626 lb/dall yearB01
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/IL0055981 · MCP: https://passage-data.com/mcp