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Somersworth W P C F

Sewage treatment plant, major discharger, Somersworth, New Hampshire. NPDES permit NH0100277 expired Oct 31, 2005; its limits still apply. Last 12 months: over a limit 2 times (last February 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 15 days after each period: form A monthly (28 values), form B quarterly (13 values)
Last report on file
September 2026
Oct 2024 – Sep 2025
2 values over a limit, 0 required values missing, 0 of 14 reports late

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

Period endingParameterReportedLimitOver by
December 2025E. coli, thermotol, MF, MTEC, daily maximum613.1 MPN/100mL≤ 406 #/100mL51%
February 2026E. coli, thermotol, MF, MTEC, daily maximum410.6 MPN/100mL≤ 406 #/100mL1%

Limits in force (74)

ParameterStatisticLimitMonths
Oxygen, dissolved [DO]daily minimum≥ 6.5 mg/LJun–Sep
BOD, 5-day, 20 deg. Cmonthly average≤ 30 mg/LJun–Sep
BOD, 5-day, 20 deg. Cmonthly average≤ 10 mg/LJun–Sep
BOD, 5-day, 20 deg. Cmonthly average≤ 30 mg/LJan, Feb, Mar, Apr, May, Oct, Nov, Dec
BOD, 5-day, 20 deg. Cweekly average≤ 45 mg/LJun–Sep
BOD, 5-day, 20 deg. Cweekly average≤ 15 mg/LJun–Sep
BOD, 5-day, 20 deg. Cweekly average≤ 45 mg/LJan, Feb, Mar, Apr, May, Oct, Nov, Dec
BOD, 5-day, 20 deg. Cdaily maximum≤ 50 mg/LJun–Sep
BOD, 5-day, 20 deg. Cdaily maximum≤ 17 mg/LJun–Sep
BOD, 5-day, 20 deg. Cdaily maximum≤ 50 mg/LJan, Feb, Mar, Apr, May, Oct, Nov, Dec
BOD, 5-day, 20 deg. Cmonthly average≤ 600 lb/dJun–Sep
BOD, 5-day, 20 deg. Cmonthly average≤ 190 lb/dJun–Sep
BOD, 5-day, 20 deg. Cmonthly average≤ 600 lb/dJan, Feb, Mar, Apr, May, Oct, Nov, Dec
BOD, 5-day, 20 deg. Cdaily maximum≤ 1001 lb/dJun–Sep
BOD, 5-day, 20 deg. Cdaily maximum≤ 317 lb/dJun–Sep
BOD, 5-day, 20 deg. Cdaily maximum≤ 1001 lb/dJan, Feb, Mar, Apr, May, Oct, Nov, Dec
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year
BOD, 5-day, 20 deg. Cweekly average≤ 901 lb/dJun–Sep
BOD, 5-day, 20 deg. Cweekly average≤ 285 lb/dJun–Sep
BOD, 5-day, 20 deg. Cweekly average≤ 901 lb/dJan, Feb, Mar, Apr, May, Oct, Nov, Dec
pHminimum≥ 6.5 SUJun–Sep
pHminimum≥ 6 SUJun–Sep
pHminimum≥ 6.5 SUJan, Feb, Mar, Apr, May, Oct, Nov, Dec
pHmaximum≤ 8 SUJun–Sep
pHmaximum≤ 8.5 SUJun–Sep
pHmaximum≤ 8 SUJan, Feb, Mar, Apr, May, Oct, Nov, Dec
Solids, total suspendedmonthly average≤ 30 mg/LJun–Sep
Solids, total suspendedmonthly average≤ 10 mg/LJun–Sep
Solids, total suspendedmonthly average≤ 30 mg/LJan, Feb, Mar, Apr, May, Oct, Nov, Dec
Solids, total suspendedweekly average≤ 45 mg/LJun–Sep
Solids, total suspendedweekly average≤ 15 mg/LJun–Sep
Solids, total suspendedweekly average≤ 45 mg/LJan, Feb, Mar, Apr, May, Oct, Nov, Dec
Solids, total suspendeddaily maximum≤ 50 mg/LJun–Sep
Solids, total suspendeddaily maximum≤ 17 mg/LJun–Sep
Solids, total suspendeddaily maximum≤ 50 mg/LJan, Feb, Mar, Apr, May, Oct, Nov, Dec
Solids, total suspendedmonthly average≤ 600 lb/dJun–Sep
Solids, total suspendedmonthly average≤ 190 lb/dJun–Sep
Solids, total suspendedmonthly average≤ 600 lb/dJan, Feb, Mar, Apr, May, Oct, Nov, Dec
Solids, total suspendeddaily maximum≤ 1001 lb/dJun–Sep
Solids, total suspendeddaily maximum≤ 317 lb/dJun–Sep
Solids, total suspendeddaily maximum≤ 1001 lb/dJan, Feb, Mar, Apr, May, Oct, Nov, Dec
Solids, total suspendedmonthly averagereport only (mg/L)all year
Solids, total suspendedweekly average≤ 901 lb/dJun–Sep
Solids, total suspendedweekly average≤ 285 lb/dJun–Sep
Solids, total suspendedweekly average≤ 901 lb/dJan, Feb, Mar, Apr, May, Oct, Nov, Dec
Nitrogen, ammonia total [as N]monthly averagereport only (mg/L)Jan, Feb, Mar, Apr, May, Oct, Nov, Dec
Nitrogen, ammonia total [as N]monthly average≤ 13 mg/LJan, Feb, Mar, Apr, May, Oct, Nov, Dec
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)Apr–Sep
Nitrogen, ammonia total [as N]weekly averagereport only (lb/d)Jun–Sep
Nitrogen, ammonia total [as N]weekly average≤ 143 lb/dJun–Sep
Nitrogen, ammonia total [as N]weekly averagereport only (lb/d)Jan, Feb, Mar, Apr, May, Oct, Nov, Dec
Nitrogen, ammonia total [as N]monthly average≤ 264 lb/dJan, Feb, Mar, Apr, May, Oct, Nov, Dec
Phosphorus, total [as P]monthly average≤ .75 mg/LMay–Sep
Phosphorus, total [as P]monthly average≤ 9.5 lb/dMay–Sep
Hardness, total [as CaCO3]daily maximumreport only (mg/L)Apr–Sep
Nickel, total recoverabledaily maximumreport only (mg/L)Apr–Sep
Zinc, total recoverabledaily maximumreport only (mg/L)Apr–Sep
Aluminum, total recoverabledaily maximumreport only (mg/L)Apr–Sep
Cadmium, total recoverabledaily maximumreport only (mg/L)Apr–Sep
Lead, total recoverabledaily maximumreport only (mg/L)Apr–Sep
Chromium, total recoverabledaily maximumreport only (mg/L)Apr–Sep
Copper, total recoverabledaily maximumreport only (mg/L)Apr–Sep
E. coli, thermotol, MF, MTECmonthly geometric mean≤ 126 #/100mLall year
E. coli, thermotol, MF, MTECdaily maximum≤ 406 #/100mLall year
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year
Flow, in conduit or thru treatment plantdaily maximumreport only (MGD)all year
Chlorine, total residualmonthly average≤ .08 mg/Lall year
Chlorine, total residualdaily maximum≤ .14 mg/Lall year
BOD, 5-day, percent removalmonthly average minimum≥ 85 %all year
Solids, suspended percent removalmonthly average minimum≥ 85 %all year
LC50 Static Renewal 48Hr Acute Ceriodaphnia dubiadaily minimum≥ 100 %Apr–Sep
LC50 Static Renewal 48Hr Acute Pimephales promelasdaily minimum≥ 100 %Apr–Sep
NOEL Static Renewal 7Day Chronic Ceriodaphnia dubiadaily minimum≥ 13.6 %Apr–Sep
Noel Statre 7Day Chronic Pimephalesdaily minimum≥ 13.6 %Apr–Sep

How strict are these limits?

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

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