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Naval Submarine Base New London

Federal facility (National Security), major discharger, Groton, Connecticut. NPDES permit CT0003921 expired Feb 28, 2017; its limits still apply. Last 12 months: over a limit 3 times (last December 2025), 1 required value missing, 1 of 127 reports late. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 30 days after each period: outfall 001 form 1 monthly (20 values), outfall 002 form 1 monthly (20 values), outfall 009 form 1 monthly (21 values), outfall 017 form 1 monthly (11 values), outfall 01H form 1 monthly (12 values)
Last report on file
August 2026
Oct 2024 – Sep 2025
8 values over a limit, 0 required values missing, 0 of 139 reports late

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

Period endingOutfallParameterReportedLimitOver by
December 2025009Flow, daily maximum5.515 MGD≤ 5 MGD10%
December 2025009Flow, maximum during 24 hr period, daily maximum5.515 MGD≤ 5 MGD10%
December 2025019Chlorine, total residual, instantaneous maximum1.06 mg/L≤ .61 mg/L74%

Limits in force (208)

ParameterStatisticLimitMonthsOutfall
Temperature, water deg. fahrenheitinstantaneous maximum≤ 90 deg FMay–Oct001
Temperature, water deg. fahrenheitinstantaneous maximum≤ 80 deg FJan, Feb, Mar, Apr, Nov, Dec001
Flow ratemonthly averagereport only (MGD)all year001
pHinstantaneous minimum≥ 6 SUall year001
pHinstantaneous maximum≤ 9 SUall year001
Solids, total suspendeddaily maximumreport only (mg/L)all year001
Oil & Greaseinstantaneous maximum≤ 10 mg/Lall year001
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)all year001
Nitrogen, nitrite total [as N]daily maximumreport only (mg/L)all year001
Nitrogen, nitrate total [as N]daily maximumreport only (mg/L)all year001
Copper, total [as Cu]daily maximum≤ .02 mg/Lall year001
Lead, total [as Pb]daily maximum≤ .01 mg/Lall year001
Nickel, total [as Ni]daily maximum≤ .01 mg/Lall year001
Zinc, total [as Zn]daily maximum≤ .034 mg/Lall year001
Flow, maximum during 24 hr perioddaily maximum≤ 15 MGDall year001
Temp. diff. between intake and dischargeinstantaneous maximum≤ 40 deg Fall year001
pH, maximuminstantaneous maximum≤ 9 SUall year001
pH, minimuminstantaneous minimum≥ 6 SUall year001
Flowdaily maximum≤ 15 MGDall year001
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)daily minimum≥ 90 %Mar, Jun, Sep, Dec001
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)daily minimumreport only (%)Jan, Feb, Apr, May, Jul, Aug, Oct, Nov001
NOAEL Static Renewal 96Hr Acute Menidia sp.daily minimum≥ 90 %Mar, Jun, Sep, Dec001
NOAEL Static Renewal 96Hr Acute Menidia sp.daily minimumreport only (%)Jan, Feb, Apr, May, Jul, Aug, Oct, Nov001
Temperature, water deg. fahrenheitinstantaneous maximum≤ 90 deg FMay–Oct002
Temperature, water deg. fahrenheitinstantaneous maximum≤ 80 deg FJan, Feb, Mar, Apr, Nov, Dec002
Flow ratemonthly averagereport only (MGD)all year002
pHinstantaneous minimum≥ 6 SUall year002
pHinstantaneous maximum≤ 9 SUall year002
Solids, total suspendeddaily maximumreport only (mg/L)all year002
Oil & Greaseinstantaneous maximum≤ 10 mg/Lall year002
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)all year002
Nitrogen, nitrite total [as N]daily maximumreport only (mg/L)all year002
Nitrogen, nitrate total [as N]daily maximumreport only (mg/L)all year002
Copper, total [as Cu]daily maximum≤ .02 mg/Lall year002
Lead, total [as Pb]daily maximum≤ .01 mg/Lall year002
Nickel, total [as Ni]daily maximum< .01 mg/Lall year002
Zinc, total [as Zn]daily maximum≤ .034 mg/Lall year002
Flow, maximum during 24 hr perioddaily maximum≤ 15 MGDall year002
Temp. diff. between intake and dischargeinstantaneous maximum≤ 25 deg Fall year002
pH, maximuminstantaneous maximum≤ 9 SUall year002
pH, minimuminstantaneous minimum≥ 6 SUall year002
Flowdaily maximum≤ 15 MGDall year002
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)daily minimum≥ 90 %Mar, Jun, Sep, Dec002
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)daily minimumreport only (%)Jan, Feb, Apr, May, Jul, Aug, Oct, Nov002
NOAEL Static Renewal 96Hr Acute Menidia sp.daily minimum≥ 90 %Mar, Jun, Sep, Dec002
NOAEL Static Renewal 96Hr Acute Menidia sp.daily minimumreport only (%)Jan, Feb, Apr, May, Jul, Aug, Oct, Nov002
pHinstantaneous minimum≥ 6 SUJan, Feb, Mar, Dec005
pHinstantaneous maximum≤ 9 SUJan, Feb, Mar, Dec005
Copper, total [as Cu]instantaneous maximum≤ .24 mg/LJan, Feb, Mar, Dec005
Lead, total [as Pb]instantaneous maximumreport only (mg/L)Jan, Feb, Mar, Dec005
Zinc, total [as Zn]instantaneous maximumreport only (mg/L)Jan, Feb, Mar, Dec005
Chlorine, total residualinstantaneous maximumreport only (mg/L)Jan, Feb, Mar, Dec005
Flowdaily maximum≤ 201600 gal/dJan, Feb, Mar, Dec005
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)instantaneous minimum> 20 %Dec005
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)instantaneous minimumreport only (%)Jan–Nov005
LC50 Static 96Hr Acute Menidiainstantaneous minimum> 20 %Dec005
LC50 Static 96Hr Acute Menidiainstantaneous minimumreport only (%)Jan–Nov005
Temperature, water deg. fahrenheitinstantaneous maximum≤ 90 deg FJul006
Temperature, water deg. fahrenheitinstantaneous maximum≤ 80 deg FJan006
pHinstantaneous minimum≥ 6 SUJan, Jul006
pHinstantaneous maximum≤ 9 SUJan, Jul006
Solids, total suspendedinstantaneous maximumreport only (mg/L)Jan, Jul006
Nitrogen, ammonia total [as N]instantaneous maximumreport only (mg/L)Jan, Jul006
Nitrogen, nitrite total [as N]instantaneous maximumreport only (mg/L)Jan, Jul006
Nitrogen, nitrate total [as N]instantaneous maximumreport only (mg/L)Jan, Jul006
Copper, total [as Cu]instantaneous maximumreport only (mg/L)Jan, Jul006
Iron, total [as Fe]instantaneous maximumreport only (mg/L)Jan, Jul006
Lead, total [as Pb]instantaneous maximumreport only (mg/L)Jan, Jul006
Nickel, total [as Ni]instantaneous maximumreport only (mg/L)Jan, Jul006
Silver, total [as Ag]instantaneous maximumreport only (mg/L)Jan, Jul006
Zinc, total [as Zn]instantaneous maximumreport only (mg/L)Jan, Jul006
Flow, maximum during 24 hr perioddaily maximum≤ 1.44 MGDJan, Jul006
Flowdaily maximum≤ 1.44 MGDJan, Jul006
Noael Static 48Hr Acute Mysid. Bahiainstantaneous minimum≥ 90 %Jan, Jul006
Noael Static 48Hr Acute Mysid. Bahiainstantaneous minimumreport only (%)Feb, Mar, Apr, May, Jun, Aug, Sep, Oct, Nov, Dec006
NOAEL Static Renewal 96Hr Acute Menidia sp.instantaneous minimum≥ 90 %Jan, Jul006
NOAEL Static Renewal 96Hr Acute Menidia sp.instantaneous minimumreport only (%)Feb, Mar, Apr, May, Jun, Aug, Sep, Oct, Nov, Dec006
BOD, 5-day, 20 deg. Cdaily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
pHinstantaneous minimum≥ 6 SUMar, Jun, Sep, Dec009
pHinstantaneous maximum≤ 9 SUMar, Jun, Sep, Dec009
Solids, total suspendeddaily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Oil & Greasedaily maximum≤ 10 mg/LMar, Jun, Sep, Dec009
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Nitrogen, nitrite total [as N]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Nitrogen, nitrate total [as N]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Copper, total [as Cu]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Iron, total [as Fe]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Lead, total [as Pb]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Nickel, total [as Ni]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Silver, total [as Ag]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Zinc, total [as Zn]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Tin, total [as Sn]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Aluminum, total [as Al]daily maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Oxidants, total residualinstantaneous maximumreport only (mg/L)Mar, Jun, Sep, Dec009
Flow, maximum during 24 hr perioddaily maximum≤ 5 MGDMar, Jun, Sep, Dec009
Flowdaily maximum≤ 5 MGDMar, Jun, Sep, Dec009
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)minimum> 41 %Mar, Jun, Sep, Dec009
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)minimumreport only (%)Jan, Feb, Apr, May, Jul, Aug, Oct, Nov009
LC50 Static 96Hr Acute Menidiaminimum> 41 %Mar, Jun, Sep, Dec009
LC50 Static 96Hr Acute Menidiaminimumreport only (%)Jan, Feb, Apr, May, Jul, Aug, Oct, Nov009
Rainfall durationdaily maximumreport only (hr/d)Jan, Jul011
Oxygen demand, chem. [low level] [COD]instantaneous maximumreport only (mg/L)Jan, Jul011
pHinstantaneous maximumreport only (SU)Jan, Jul011
Solids, total suspendedinstantaneous maximumreport only (mg/L)Jan, Jul011
Oil & Greaseinstantaneous maximumreport only (mg/L)Jan, Jul011
Nitrogen, nitrate total [as N]instantaneous maximumreport only (mg/L)Jan, Jul011
Nitrogen, Kjeldahl, total [as N]instantaneous maximumreport only (mg/L)Jan, Jul011
Phosphorus, total [as P]instantaneous maximumreport only (mg/L)Jan, Jul011
Cadmium, total [as Cd]instantaneous maximumreport only (mg/L)Jan, Jul011
Chromium, total [as Cr]instantaneous maximumreport only (mg/L)Jan, Jul011
Copper, total [as Cu]instantaneous maximumreport only (mg/L)Jan, Jul011
Iron, total [as Fe]instantaneous maximumreport only (mg/L)Jan, Jul011
Lead, total [as Pb]instantaneous maximumreport only (mg/L)Jan, Jul011
Nickel, total [as Ni]instantaneous maximumreport only (mg/L)Jan, Jul011
Silver, total [as Ag]instantaneous maximumreport only (mg/L)Jan, Jul011
Zinc, total [as Zn]instantaneous maximumreport only (mg/L)Jan, Jul011
Tin, total [as Sn]instantaneous maximumreport only (mg/L)Jan, Jul011
Aluminum, total [as Al]instantaneous maximumreport only (mg/L)Jan, Jul011
Rainfalldaily maximumreport only (in)Jan, Jul011
Flowdaily maximumreport only (gal/d)Jan, Jul011
LC50 Static 48Hr Acute D. Pulexminimumreport only (%)Jan, Jul011
LC50 Static 48Hr Acute D. Pulexminimumreport only (%)Feb, Mar, Apr, May, Jun, Aug, Sep, Oct, Nov, Dec011
LC50 Static 48Hr Acute Pimephales promelasminimumreport only (%)Jan, Jul011
LC50 Static 48Hr Acute Pimephales promelasminimumreport only (%)Feb, Mar, Apr, May, Aug, Sep, Oct, Nov, Dec011
pHinstantaneous minimum≥ 6 SUJan, Jul012
pHinstantaneous maximum≤ 9 SUJan, Jul012
Solids, total suspendedinstantaneous maximumreport only (mg/L)Jan, Jul012
Oil & Greaseinstantaneous maximum≤ 10 mg/LJan, Jul012
Copper, total [as Cu]instantaneous maximumreport only (mg/L)Jan, Jul012
Iron, total [as Fe]instantaneous maximumreport only (mg/L)Jan, Jul012
Lead, total [as Pb]instantaneous maximumreport only (mg/L)Jan, Jul012
Zinc, total [as Zn]instantaneous maximumreport only (mg/L)Jan, Jul012
Surfactants [MBAS]instantaneous maximumreport only (mg/L)Jan, Jul012
Flowdaily maximumreport only (gal/d)Jan, Jul012
Cyclohexylamineinstantaneous maximumreport only (mg/L)Jan, Jul012
LC50 Static 48Hr Acute D. Pulexminimumreport only (%)Jan, Jul012
LC50 Static 48Hr Acute D. Pulexminimumreport only (%)Feb, Mar, May, Jun, Aug, Sep, Oct, Nov, Dec012
LC50 Static 96Hr Acute Pimephalesminimumreport only (%)Jan, Jul012
LC50 Static 96Hr Acute Pimephalesminimumreport only (%)Feb, Mar, Apr, May, Jun, Aug, Sep, Oct, Nov, Dec012
pHinstantaneous minimum≥ 6 SUJan, Jul014
pHinstantaneous maximum≤ 9 SUJan, Jul014
Solids, total suspendedinstantaneous maximumreport only (mg/L)Jan, Jul014
Oil & Greaseinstantaneous maximum≤ 10 mg/LJan, Jul014
Copper, total [as Cu]instantaneous maximumreport only (mg/L)Jan, Jul014
Iron, total [as Fe]instantaneous maximumreport only (mg/L)Jan, Jul014
Lead, total [as Pb]instantaneous maximumreport only (mg/L)Jan, Jul014
Zinc, total [as Zn]instantaneous maximumreport only (mg/L)Jan, Jul014
Surfactants [MBAS]instantaneous maximumreport only (mg/L)Jan, Jul014
Flowdaily maximumreport only (gal/d)Jan, Jul014
Cyclohexylamineinstantaneous maximumreport only (mg/L)Jan, Jul014
LC50 Static 48Hr Acute D. Pulexminimumreport only (%)Jan, Jul014
LC50 Static 48Hr Acute D. Pulexminimumreport only (%)Feb, Mar, Apr, May, Jun, Aug, Sep, Oct, Nov, Dec014
LC50 Static 96Hr Acute Pimephalesminimumreport only (%)Jan, Jul014
LC50 Static 96Hr Acute Pimephalesminimumreport only (%)Feb, Mar, Apr, May, Jun, Aug, Sep, Oct, Nov, Dec014
pHinstantaneous minimum≥ 6 SUJan, Jul015
pHinstantaneous maximum≤ 9 SUJan, Jul015
Solids, total suspendedinstantaneous maximumreport only (mg/L)Jan, Jul015
Oil & Greaseinstantaneous maximum≤ 10 mg/LJan, Jul015
Copper, total [as Cu]instantaneous maximumreport only (mg/L)Jan, Jul015
Iron, total [as Fe]instantaneous maximumreport only (mg/L)Jan, Jul015
Lead, total [as Pb]instantaneous maximumreport only (mg/L)Jan, Jul015
Zinc, total [as Zn]instantaneous maximumreport only (mg/L)Jan, Jul015
Surfactants [MBAS]instantaneous maximumreport only (mg/L)Jan, Jul015
Flowdaily maximumreport only (gal/d)Jan, Jul015
Cyclohexylamineinstantaneous maximumreport only (mg/L)Jan, Jul015
LC50 Static 48Hr Acute D. Pulexminimumreport only (%)Jan, Jul015
LC50 Static 48Hr Acute D. Pulexminimumreport only (%)Feb, Mar, Apr, May, Jun, Aug, Sep, Oct, Nov, Dec015
LC50 Static 96Hr Acute Pimephalesminimumreport only (%)Jan, Jul015
LC50 Static 96Hr Acute Pimephalesminimumreport only (%)Feb, Mar, Apr, May, Jun, Aug, Sep, Oct, Nov, Dec015
Temperature, water deg. fahrenheitinstantaneous maximumreport only (deg F)Jan, Feb, Mar, Sep, Oct, Nov, Dec017
pHinstantaneous minimum≥ 6 SUJan, Feb, Mar, Sep, Oct, Nov, Dec017
pHinstantaneous maximum≤ 9 SUJan, Feb, Mar, Sep, Oct, Nov, Dec017
Solids, total suspendedinstantaneous maximumreport only (mg/L)Jan, Feb, Mar, Sep, Oct, Nov, Dec017
Copper, total [as Cu]instantaneous maximumreport only (mg/L)Jan, Feb, Mar, Sep, Oct, Nov, Dec017
Iron, total [as Fe]instantaneous maximumreport only (mg/L)Jan, Feb, Mar, Sep, Oct, Nov, Dec017
Lead, total [as Pb]instantaneous maximumreport only (mg/L)Jan, Feb, Mar, Sep, Oct, Nov, Dec017
Zinc, total [as Zn]instantaneous maximumreport only (mg/L)Jan, Feb, Mar, Sep, Oct, Nov, Dec017
Cyclohexylamineinstantaneous maximumreport only (mg/L)Jan, Feb, Mar, Sep, Oct, Nov, Dec017
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)minimumreport only (%)Jan, Feb, Mar, Sep, Oct, Nov, Dec017
LC50 Static 96Hr Acute Menidiaminimumreport only (%)Jan, Feb, Mar, Sep, Oct, Nov, Dec017
pHinstantaneous minimum≥ 6 SUDec019
pHinstantaneous maximum≤ 9 SUDec019
Copper, total [as Cu]instantaneous maximumreport only (mg/L)Dec019
Iron, total [as Fe]instantaneous maximumreport only (mg/L)Dec019
Lead, total [as Pb]instantaneous maximumreport only (mg/L)Dec019
Nickel, total [as Ni]instantaneous maximumreport only (mg/L)Dec019
Zinc, total [as Zn]instantaneous maximumreport only (mg/L)Dec019
Flow, maximum during 24 hr perioddaily maximumreport only (gal/d)Dec019
Chlorine, total residualinstantaneous maximum≤ .61 mg/LDec019
Flowdaily maximumreport only (gal/d)Dec019
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)minimumreport only (%)Dec019
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)minimumreport only (%)Jan–Nov019
LC50 Static 96Hr Acute Menidiaminimumreport only (%)Dec019
LC50 Static 96Hr Acute Menidiaminimumreport only (%)Jan–Nov019
Temperature, water deg. fahrenheitinstantaneous maximumreport only (deg F)all year01H
pHinstantaneous maximumreport only (SU)all year01H
Solids, total suspendeddaily maximumreport only (mg/L)all year01H
Oil & Greaseinstantaneous maximumreport only (mg/L)all year01H
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)all year01H
Nitrogen, nitrite total [as N]daily maximumreport only (mg/L)all year01H
Nitrogen, nitrate total [as N]daily maximumreport only (mg/L)all year01H
Copper, total [as Cu]daily maximumreport only (mg/L)all year01H
Lead, total [as Pb]daily maximumreport only (mg/L)all year01H
Zinc, total [as Zn]daily maximumreport only (mg/L)all year01H
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)daily minimumreport only (%)Mar, Jun, Sep, Dec01H
LC50 Static 48Hr Acute Americamysis bahia (formerly Mysidopsis bahia)daily minimumreport only (%)Jan, Feb, Apr, May, Jul, Aug, Oct, Nov01H
NOAEL Static Renewal 96Hr Acute Menidia sp.daily minimumreport only (%)Mar, Jun, Sep, Dec01H
NOAEL Static Renewal 96Hr Acute Menidia sp.daily minimumreport only (%)Jan, Feb, Apr, May, Jul, Aug, Oct, Nov01H

How strict are these limits?

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

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Your permit document is the final word. As JSON: /api/v1/permits/CT0003921 · MCP: https://passage-data.com/mcp