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New Canaan STP

Sewage treatment plant, major discharger, New Canaan, Connecticut. NPDES permit CT0101273 expired Jan 31, 2026; its limits still apply. Last 12 months: no values over a limit. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 31 days after each period: form 1 monthly (63 values)
Last report on file
September 2026
Oct 2024 – Sep 2025
0 values over a limit, 0 required values missing, 0 of 12 reports late

Limits in force (113)

ParameterStatisticLimitMonths
Flow ratemonthly averagereport only (MGD)all year
Flow ratedaily maximumreport only (MGD)all year
Oxygen, dissolved [DO]instantaneous minimum≥ 6 mg/Lall year
BOD, 5-day, 20 deg. Cmonthly average≤ 20 mg/LJan, Feb, Mar, Apr, Nov, Dec
BOD, 5-day, 20 deg. Cmonthly average≤ 10 mg/LMay–Oct
BOD, 5-day, 20 deg. Cdaily maximum≤ 30 mg/LJan, Feb, Mar, Apr, Nov, Dec
BOD, 5-day, 20 deg. Cdaily maximum≤ 15 mg/LMay–Oct
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year
BOD, 5-day, 20 deg. Cdaily maximumreport only (mg/L)Jan, Apr, Jul, Oct
BOD, 5-day, 20 deg. Cdaily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
pHinstantaneous minimum≥ 6 SUall year
pHinstantaneous maximum≤ 9 SUall year
Solids, total suspendedmonthly average≤ 11 mg/LMay–Oct
Solids, total suspendedmonthly average≤ 13 mg/LJan, Feb, Mar, Apr, Nov, Dec
Solids, total suspendeddaily maximum≤ 16.5 mg/LMay–Oct
Solids, total suspendeddaily maximum≤ 19.5 mg/LJan, Feb, Mar, Apr, Nov, Dec
Solids, total suspendedmonthly averagereport only (mg/L)all year
Solids, total suspendeddaily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Solids, total suspendeddaily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Nitrogen, ammonia total [as N]monthly average≤ 1.1 mg/LJun–Sep
Nitrogen, ammonia total [as N]monthly average≤ 1.9 mg/LOct
Nitrogen, ammonia total [as N]monthly average≤ 3.6 mg/LMay
Nitrogen, ammonia total [as N]daily maximum≤ 2.2 mg/LJun–Sep
Nitrogen, ammonia total [as N]daily maximum≤ 3.8 mg/LOct
Nitrogen, ammonia total [as N]daily maximum≤ 6.2 mg/LMay
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Nitrogen, nitrite total [as N]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Nitrogen, nitrite total [as N]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Nitrogen, nitrate total [as N]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Nitrogen, nitrate total [as N]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Phosphorus, total [as P]monthly average≤ .29 mg/LApr–Oct
Phosphorus, total [as P]daily maximum≤ .59 mg/LApr–Oct
Phosphorus, total [as P]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Phosphorus, total [as P]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Cyanide, total [as CN]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Cyanide, total [as CN]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Cyanide, free [amenable to chlorination]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Cyanide, free [amenable to chlorination]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Arsenic, total [as As]instantaneous maximumreport only (mg/kg)Jan, Apr, Jul, Oct
Arsenic, total [as As]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Arsenic, total [as As]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Beryllium, total [as Be]instantaneous maximumreport only (mg/kg)Jan, Apr, Jul, Oct
Beryllium, total [as Be]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Beryllium, total [as Be]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Cadmium, total [as Cd]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Cadmium, total [as Cd]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Chromium, hexavalent [as Cr]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Chromium, hexavalent [as Cr]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Chromium, total [as Cr]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Chromium, total [as Cr]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Copper, total [as Cu]monthly averagereport only (mg/L)all year
Copper, total [as Cu]daily maximumreport only (mg/L)all year
Copper, total [as Cu]monthly average≤ .125 kg/dall year
Copper, total [as Cu]daily maximum≤ .287 kg/dall year
Copper, total [as Cu]monthly averagereport only (mg/L)all year
Copper, total [as Cu]daily maximumreport only (mg/L)all year
Copper, total [as Cu]monthly averagereport only (kg/d)all year
Copper, total [as Cu]daily maximumreport only (kg/d)all year
Copper, total [as Cu]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Copper, total [as Cu]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Iron, total [as Fe]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Iron, total [as Fe]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Lead, total [as Pb]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Lead, total [as Pb]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Thallium, total [as Tl]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Thallium, total [as Tl]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Nickel, total [as Ni]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Nickel, total [as Ni]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Silver, total [as Ag]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Silver, total [as Ag]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Zinc, total [as Zn]monthly average≤ .3 kg/dall year
Zinc, total [as Zn]daily maximum≤ .45 kg/dall year
Zinc, total [as Zn]monthly averagereport only (mg/L)all year
Zinc, total [as Zn]daily maximumreport only (mg/L)all year
Zinc, total [as Zn]monthly averagereport only (kg/d)all year
Zinc, total [as Zn]daily maximumreport only (kg/d)all year
Zinc, total [as Zn]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Zinc, total [as Zn]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Antimony, total [as Sb]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Antimony, total [as Sb]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Aluminum, total [as Al]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Aluminum, total [as Al]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Selenium, total [as Se]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Selenium, total [as Se]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Polychlorinated biphenyls [PCBs]instantaneous maximumreport only (mg/kg)Jan, Apr, Jul, Oct
Phenolsdaily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Phenolsdaily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Chlorine, total residualdaily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Chlorine, total residualdaily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
E. coli30-day geometric mean≤ 126 #/100mLall year
E. colimaximum≤ 410 #/100mLall year
Phosphorus, Total [Avg Seasonal Load Cap]monthly average≤ 1.47 lb/dOct
Solids, total, percentinstantaneous minimumreport only (%)Jan, Apr, Jul, Oct
Solids, fixed, % of total solidsinstantaneous minimumreport only (%)Jan, Apr, Jul, Oct
Solids, volatile % of total solidsinstantaneous minimumreport only (%)Jan, Apr, Jul, Oct
Mercury, total [as Hg]daily maximumreport only (mg/L)Jan, Apr, Jul, Oct
Mercury, total [as Hg]daily maximumreport only (mg/L)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
Zinc, sludge, total, dry weight [as Zn]instantaneous maximumreport only (mg/kg)Jan, Apr, Jul, Oct
Lead, sludge, total, dry weight [as Pb]instantaneous maximumreport only (mg/kg)Jan, Apr, Jul, Oct
Nickel, sludge, total, dry weight [as Ni]instantaneous maximumreport only (mg/kg)Jan, Apr, Jul, Oct
Mercury, sludge, total, dry weight [as Hg]instantaneous maximumreport only (mg/kg)Jan, Apr, Jul, Oct
Chromium, sludge, total, dry weight [as Cr]instantaneous maximumreport only (mg/kg)Jan, Apr, Jul, Oct
Copper, sludge, total, dry weight [as Cu]instantaneous maximumreport only (mg/kg)Jan, Apr, Jul, Oct
Cadmium, sludge, total, dry weight [as Cd]instantaneous maximumreport only (mg/kg)Jan, Apr, Jul, Oct
BOD, carbonaceous [5 day, 5 C]monthly averagereport only (mg/L)all year
BOD, carbonaceous [5 day, 5 C]daily minimumreport only (mg/L)all year
BOD, 5-day, percent removalminimum % removal≥ 85 %all year
Solids, suspended percent removalminimum % removal≥ 85 %all year
NOAEL Static 48Hr Acute D. pulexinstantaneous minimum≥ 90 % survivalJan, Apr, Jul, Oct
NOAEL Static 48Hr Acute D. pulexinstantaneous minimumreport only (% survival)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec
NOAEL Static 48Hr Acute Pimephales promelasinstantaneous minimum≥ 90 % survivalJan, Apr, Jul, Oct
NOAEL Static 48Hr Acute Pimephales promelasinstantaneous minimumreport only (% survival)Feb, Mar, May, Jun, Aug, Sep, Nov, Dec

How strict are these limits?

Cited limits by parameter: Connecticut'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/CT0101273 · MCP: https://passage-data.com/mcp