CHARLESTON WATER SYSTEM

NPDES permit SC0021229 · Major POTW · administratively continued, expires 2024-07-31 · EPA's file as of 2026-09-19

Check this month's numbers before you file
Watch this permit — $79 a month. Every Monday, from EPA's newest files: the next report due and when, whether EPA's file holds your last one, any change to this permit's limits or status, and the renewal date.

This permit expired on 2024-07-31 and is administratively continued: its last limits keep applying until a new permit is issued, and EPA still expects the reports.

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

1values over a limit
0required values missing, on 0 form(s)
0of 13 forms filed late

Last period with anything received: 2026-07-31. Most often over: Enterococci (1).

Reporting

Reports are due about 29 days after each monitoring period ends (the most common figure among SC permits in EPA's filings — check your permit).

Limits in force (46)

OutfallParameterStatisticLimitMonths
001Oxygen demand, ultimateMO AVG <= 42064 lb/d Jan, Feb, Nov, Dec
001Oxygen demand, ultimateMO AVG <= 24612 lb/d Mar, Apr, May, Jun, Jul, Aug, Sep, Oct
001Oxygen demand, ultimateWKLY AVG <= 63096 lb/d Jan, Feb, Nov, Dec
001Oxygen demand, ultimateWKLY AVG <= 36918 lb/d Mar, Apr, May, Jun, Jul, Aug, Sep, Oct
001Oxygen, dissolved [DO]MINIMUM >= 1 mg/L all year
001Oxygen, dissolved [DO]MO AV MN >= 4 mg/L all year
001pHMINIMUM >= 6 SU all year
001pHMAXIMUM <= 8.5 SU all year
001Solids, total suspendedMO AVG <= 30 mg/L all year
001Solids, total suspendedWKLY AVG <= 45 mg/L all year
001Solids, total suspendedMO AVG <= 9007 lb/d all year
001Solids, total suspendedWKLY AVG <= 13511 lb/d all year
001Nitrogen, total [as N]MO AVG report only all year
001Nitrogen, total [as N]WKLY AVG report only all year
001Nitrogen, total [as N]MO AVG report only all year
001Nitrogen, total [as N]WKLY AVG report only all year
001Nitrogen, ammonia total [as N]MO AVG report only Jan, Feb, Nov, Dec
001Nitrogen, ammonia total [as N]MO AVG <= 17 mg/L Mar, Apr, May, Jun, Jul, Aug, Sep, Oct
001Nitrogen, ammonia total [as N]WKLY AVG report only Jan, Feb, Nov, Dec
001Nitrogen, ammonia total [as N]WKLY AVG <= 26 mg/L Mar, Apr, May, Jun, Jul, Aug, Sep, Oct
001Nitrogen, ammonia total [as N]MO AVG report only Jan, Feb, Nov, Dec
001Nitrogen, ammonia total [as N]MO AVG <= 5104 lb/d Mar, Apr, May, Jun, Jul, Aug, Sep, Oct
001Nitrogen, ammonia total [as N]WKLY AVG report only Jan, Feb, Nov, Dec
001Nitrogen, ammonia total [as N]WKLY AVG <= 7806 lb/d Mar, Apr, May, Jun, Jul, Aug, Sep, Oct
001Phosphorus, total [as P]MO AVG report only all year
001Phosphorus, total [as P]WKLY AVG report only all year
001Phosphorus, total [as P]MO AVG report only all year
001Phosphorus, total [as P]WKLY AVG report only all year
001Flow, in conduit or thru treatment plantMO AVG report only all year
001Flow, in conduit or thru treatment plantWKLY AVG report only all year
001Chlorine, total residualMO AVG report only all year
001Chlorine, total residualDAILY MX report only all year
001Chlorine, total residualMO AVG <= .5 mg/L all year
001Chlorine, total residualDAILY MX <= 1 mg/L all year
001Enterococci30DAVGEO <= 35 MPN/100mL all year
001EnterococciDAILY MX <= 501 MPN/100mL all year
001Enterococci30DAVGEO <= 35 MPN/100mL all year
001EnterococciDAILY MX <= 800 MPN/100mL all year
001BOD, carbonaceous [5 day, 20 C]MO AVG <= 25 mg/L all year
001BOD, carbonaceous [5 day, 20 C]WKLY AVG <= 40 mg/L all year
001BOD, carbonaceous [5 day, 20 C]MO AVG <= 7506 lb/d all year
001BOD, carbonaceous [5 day, 20 C]WKLY AVG <= 12010 lb/d all year
001Solids, suspended percent removalMO AV MN >= 85 % all year
001Carbonaceous oxygen demand, % removalMO AV MN >= 85 % all year
001% Effect Static Renewal 7 Day Chronic Americamysis bahia (formerly Mysidopsis bahia)MO AVG <= 25 % all year
001% Effect Static Renewal 7 Day Chronic Americamysis bahia (formerly Mysidopsis bahia)DAILY MX <= 40 % all year

Built from EPA's ECHO bulk files. EPA's file, not the permit document, is the source: read your permit. Check a report before you file it · All states