CHARLESTOWN WASTEWATER TREATMENT PLANT — NPDES permit IN0020508: limits, due date and EPA's record

NPDES permit IN0020508 · Major POTW · effective, expires 2031-01-31 · EPA's file as of 2026-09-19

EPA's record, 2025-09-01 to 2026-08-31

Last period with anything received: 2026-07-31. Most often over: Nitrogen, ammonia total [as N] (2), E. coli, colony forming units [CFU] (1).

Reporting

Reports are due about 28 days after each monitoring period ends (read off this permit's own late-day counts in EPA's filings).

Limits in force (39)

Outfall	Parameter	Statistic	Limit	Months
009	Oxygen, dissolved [DO]	DLYAVMIN	>= 6 mg/L	all year
009	pH	DAILY MN	>= 6 SU	all year
009	pH	DAILY MX	<= 9 SU	all year
009	Solids, total suspended	MO AVG	<= 12 mg/L	all year
009	Solids, total suspended	MX WK AV	<= 18 mg/L	all year
009	Solids, total suspended	MO AVG	<= 400 lb/d	all year
009	Solids, total suspended	MX WK AV	<= 600 lb/d	all year
009	Nitrogen, total [as N]	MO AVG	report only	all year
009	Nitrogen, total [as N]	MO AVG	report only	all year
009	Nitrogen, ammonia total [as N]	MO AVG	<= 1.1 mg/L	May, Jun, Jul, Aug, Sep, Oct, Nov
009	Nitrogen, ammonia total [as N]	MO AVG	<= 1.6 mg/L	Jan, Feb, Mar, Apr, Dec
009	Nitrogen, ammonia total [as N]	MX WK AV	<= 1.6 mg/L	May, Jun, Jul, Aug, Sep, Oct, Nov
009	Nitrogen, ammonia total [as N]	MX WK AV	<= 2.4 mg/L	Jan, Feb, Mar, Apr, Dec
009	Nitrogen, ammonia total [as N]	MO AVG	<= 37 lb/d	May, Jun, Jul, Aug, Sep, Oct, Nov
009	Nitrogen, ammonia total [as N]	MO AVG	<= 53 lb/d	Jan, Feb, Mar, Apr, Dec
009	Nitrogen, ammonia total [as N]	MX WK AV	<= 53 lb/d	May, Jun, Jul, Aug, Sep, Oct, Nov
009	Nitrogen, ammonia total [as N]	MX WK AV	<= 80 lb/d	Jan, Feb, Mar, Apr, Dec
009	Phosphorus, total [as P]	MO AVG	<= 1 mg/L	all year
009	Phosphorus, total [as P]	MO AVG	report only	all year
009	Flow, in conduit or thru treatment plant	MO AVG	report only	all year
009	E. coli, colony forming units [CFU]	MO GEO	<= 125 CFU/100mL	Apr, May, Jun, Jul, Aug, Sep, Oct
009	E. coli, colony forming units [CFU]	DAILY MX	<= 235 CFU/100mL	Apr, May, Jun, Jul, Aug, Sep, Oct
009	Toxicity [acute], Ceriodaphnia dubia	MAXIMUM	<= 1 tox acute	Jul
009	Toxicity [acute], Ceriodaphnia dubia	MAXIMUM	<= 1 tox acute	Jul
009	Toxicity [acute], Ceriodaphnia dubia	MAXIMUM	<= 1 tox acute	Aug
009	Toxicity [chronic], Ceriodaphnia dubia	MAXIMUM	<= 1 tox chronic	Jul
009	Toxicity [chronic], Ceriodaphnia dubia	MAXIMUM	<= 1 tox chronic	Jul
009	Toxicity [chronic], Ceriodaphnia dubia	MAXIMUM	<= 1 tox chronic	Aug
009	Toxicity [acute], Pimephales promelas [Fathead Minnow]	MAXIMUM	<= 1 tox acute	Jul
009	Toxicity [acute], Pimephales promelas [Fathead Minnow]	MAXIMUM	<= 1 tox acute	Jul
009	Toxicity [acute], Pimephales promelas [Fathead Minnow]	MAXIMUM	<= 1 tox acute	Aug
009	Toxicity [chronic], Pimephales promelas [Fathead Minnow]	MAXIMUM	<= 1 tox chronic	Jul
009	Toxicity [chronic], Pimephales promelas [Fathead Minnow]	MAXIMUM	<= 1 tox chronic	Jul
009	Toxicity [chronic], Pimephales promelas [Fathead Minnow]	MAXIMUM	<= 1 tox chronic	Aug
009	BOD, carbonaceous [5 day, 20 C]	MO AVG	<= 10 mg/L	all year
009	BOD, carbonaceous [5 day, 20 C]	MX WK AV	<= 15 mg/L	all year
009	BOD, carbonaceous [5 day, 20 C]	MO AVG	<= 330 lb/d	all year
009	BOD, carbonaceous [5 day, 20 C]	MX WK AV	<= 500 lb/d	all year
009	Flow, total	MO TOTAL	report only	all year