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Derry W W T P

Sewage treatment plant, major discharger, Derry, New Hampshire. NPDES permit NH0100056 expired Feb 29, 2016; its limits still apply. Last 12 months: over a limit 4 times (last July 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 15 days after each period: form A monthly (33 values), form B quarterly (11 values)
Last report on file
September 2026
Oct 2024 – Sep 2025
5 values over a limit, 0 required values missing, 1 of 14 reports late

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

Period endingParameterReportedLimitOver by
March 2026LC50 Static Renewal 48Hr Acute Pimephales promelas, daily minimum70.7 %≥ 100 %29%
May 2026pH, maximum8.1 SU≤ 8 SU—
June 2026pH, minimum5.4 SU≥ 6.5 SU—
July 2026pH, minimum5.2 SU≥ 6.5 SU—

Limits in force (44)

ParameterStatisticLimitMonths
pHminimum≥ 6.5 SUall year
pHmaximum≤ 8 SUall year
Solids, total suspendedmonthly average≤ 30 mg/Lall year
Solids, total suspendedweekly average≤ 45 mg/Lall year
Solids, total suspendeddaily maximum≤ 50 mg/Lall year
Solids, total suspendedmonthly average≤ 1024 lb/dall year
Solids, total suspendeddaily maximum≤ 1707 lb/dall year
Solids, total suspendedmonthly averagereport only (mg/L)all year
Solids, total suspendeddaily maximumreport only (mg/L)all year
Solids, total suspendedmonthly averagereport only (lb/d)all year
Solids, total suspendeddaily maximumreport only (lb/d)all year
Solids, total suspendedweekly average≤ 1536 lb/dall year
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)Jan, Feb, Mar, Jul, Aug, Sep
Phosphorus, total [as P]daily maximumreport only (mg/L)all year
Hardness, total [as CaCO3]daily maximumreport only (mg/L)Jan, Feb, Mar, Jul, Aug, Sep
Arsenic, total recoverablemonthly averagereport only (ug/L)all year
Arsenic, total recoverabledaily maximumreport only (ug/L)all year
Nickel, total recoverabledaily maximumreport only (ug/L)Jan, Feb, Mar, Jul, Aug, Sep
Zinc, total recoverabledaily maximumreport only (ug/L)Jan, Feb, Mar, Jul, Aug, Sep
Aluminum, total recoverabledaily maximumreport only (ug/L)Jan, Feb, Mar, Jul, Aug, Sep
Cadmium, total recoverabledaily maximumreport only (ug/L)Jan, Feb, Mar, Jul, Aug, Sep
Lead, total recoverabledaily maximumreport only (ug/L)Jan, Feb, Mar, Jul, Aug, Sep
Chromium, total recoverabledaily maximumreport only (ug/L)Jan, Feb, Mar, Jul, Aug, Sep
Copper, total recoverabledaily maximumreport only (ug/L)Jan, Feb, Mar, Jul, Aug, Sep
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≤ 1 mg/Lall year
Chlorine, total residualdaily maximum≤ 1 mg/Lall year
E. coli, colony forming units [CFU]monthly geometric mean≤ 126 CFU/100mLall year
E. coli, colony forming units [CFU]daily maximum≤ 406 CFU/100mLall year
BOD, carbonaceous [5 day, 20 C]monthly average≤ 25 mg/Lall year
BOD, carbonaceous [5 day, 20 C]weekly average≤ 40 mg/Lall year
BOD, carbonaceous [5 day, 20 C]daily maximum≤ 45 mg/Lall year
BOD, carbonaceous [5 day, 20 C]monthly average≤ 853 lb/dall year
BOD, carbonaceous [5 day, 20 C]daily maximum≤ 1536 lb/dall year
BOD, carbonaceous [5 day, 20 C]monthly averagereport only (mg/L)all year
BOD, carbonaceous [5 day, 20 C]daily maximumreport only (mg/L)all year
BOD, carbonaceous [5 day, 20 C]monthly averagereport only (lb/d)all year
BOD, carbonaceous [5 day, 20 C]daily maximumreport only (lb/d)all year
BOD, carbonaceous [5 day, 20 C]weekly average≤ 1365 lb/dall year
BOD, carb-5 day, 20 deg C, 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 %Jan, Feb, Mar, Jul, Aug, Sep
LC50 Static Renewal 48Hr Acute Pimephales promelasdaily minimum≥ 100 %Jan, Feb, Mar, Jul, Aug, Sep

How strict are these limits?

Cited limits by parameter: New Hampshire'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/NH0100056 · MCP: https://passage-data.com/mcp