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Darlington City of

Sewage treatment plant, major discharger, Darlington, South Carolina. NPDES permit SC0039624 expired Aug 31, 2016; its limits still apply. Last 12 months: over a limit 23 times (last August 2026), 2 of 13 reports late. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 29 days after each period: form 1 monthly (31 values), form 2 yearly, form 3 yearly
Last report on file
August 2026
Oct 2024 – Sep 2025
1 value over a limit, 0 required values missing, 0 of 14 reports late

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

All 23 values over a limit
Period endingParameterReportedLimitOver by
December 2025Solids, suspended percent removal, monthly average minimum84≥ 85 %7%
March 2026BOD, 5-day, percent removal, monthly average minimum82≥ 85 %20%
April 2026BOD, 5-day, 20 deg. C, monthly average42.1≤ 30 mg/L40%
April 2026BOD, 5-day, 20 deg. C, weekly average49.8≤ 45 mg/L11%
April 2026BOD, 5-day, percent removal, monthly average minimum74≥ 85 %73%
May 2026BOD, 5-day, 20 deg. C, monthly average> 367≤ 400 lb/d—
May 2026BOD, 5-day, 20 deg. C, monthly average> 55.7≤ 30 mg/L—
May 2026BOD, 5-day, 20 deg. C, weekly average> 502≤ 600 lb/d—
May 2026BOD, 5-day, 20 deg. C, weekly average> 66.8≤ 45 mg/L—
May 2026BOD, 5-day, percent removal, monthly average minimum76≥ 85 %60%
June 2026BOD, 5-day, 20 deg. C, monthly average> 309≤ 400 lb/d—
June 2026BOD, 5-day, 20 deg. C, monthly average> 59.6≤ 30 mg/L—
June 2026BOD, 5-day, 20 deg. C, weekly average669≤ 600 lb/d11%
June 2026BOD, 5-day, 20 deg. C, weekly average80.3≤ 45 mg/L78%
June 2026BOD, 5-day, percent removal, monthly average minimum68≥ 85 %113%
June 2026Solids, suspended percent removal, monthly average minimum83≥ 85 %13%
July 2026BOD, 5-day, 20 deg. C, monthly average41.4≤ 30 mg/L38%
July 2026BOD, 5-day, 20 deg. C, weekly average92.8≤ 45 mg/L106%
July 2026BOD, 5-day, percent removal, monthly average minimum79≥ 85 %40%
August 2026BOD, 5-day, 20 deg. C, monthly average33.7≤ 30 mg/L12%
August 2026BOD, 5-day, 20 deg. C, weekly average46.6≤ 45 mg/L4%
August 2026BOD, 5-day, percent removal, monthly average minimum68≥ 85 %113%
August 2026Solids, suspended percent removal, monthly average minimum80≥ 85 %33%

Limits in force (37)

ParameterStatisticLimitMonths
Oxygen, dissolved [DO]instantaneous minimum≥ 2 mg/Lall year
BOD, 5-day, 20 deg. Cmonthly average≤ 30 mg/Lall year
BOD, 5-day, 20 deg. Cweekly average≤ 45 mg/Lall year
BOD, 5-day, 20 deg. Cmonthly average≤ 400 lb/dall year
BOD, 5-day, 20 deg. Cweekly average≤ 600 lb/dall year
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year
BOD, 5-day, 20 deg. Cweekly averagereport only (mg/L)all year
pHminimum≥ 6 SUall year
pHmaximum≤ 8.5 SUall year
Solids, total suspendedmonthly average≤ 30 mg/Lall year
Solids, total suspendedweekly average≤ 45 mg/Lall year
Solids, total suspendedmonthly average≤ 400 lb/dall year
Solids, total suspendedweekly average≤ 600 lb/dall year
Solids, total suspendedmonthly averagereport only (mg/L)all year
Solids, total suspendedweekly averagereport only (mg/L)all year
Nitrogen, ammonia total [as N]monthly averagereport only (mg/L)all year
Nitrogen, ammonia total [as N]weekly averagereport only (mg/L)all year
Nitrogen, ammonia total [as N]monthly averagereport only (lb/d)all year
Nitrogen, ammonia total [as N]weekly averagereport only (lb/d)all year
Flow, in conduit or thru treatment plantmonthly averagereport only (MGD)all year
Flow, in conduit or thru treatment plantweekly averagereport only (MGD)all year
Chlorine, total residualmonthly average≤ .32 mg/Lall year
Chlorine, total residualdaily maximum≤ .55 mg/Lall year
Chlorine, total residualmonthly average≤ 4.27 lb/dall year
Chlorine, total residualdaily maximum≤ 7.34 lb/dall year
Mercury, total [as Hg]monthly averagereport only (mg/L)all year
Mercury, total [as Hg]daily maximumreport only (mg/L)all year
Mercury, total [as Hg]monthly averagereport only (lb/d)all year
Mercury, total [as Hg]daily maximumreport only (lb/d)all year
Coliform, fecal general30-day geometric mean≤ 200 #/100mLall year
Coliform, fecal generaldaily maximum≤ 400 #/100mLall year
BOD, 5-day, percent removalmonthly average minimum≥ 85 %all year
Solids, suspended percent removalmonthly average minimum≥ 85 %all year
Flow, totalmonthly average≤ 6.1 MGDall year
Flow, totalweekly average≤ 6.1 MGDall year
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiamonthly average≤ 25 %all year
%Effect Static Renewal 7 Day Chronic Ceriodaphnia dubiadaily maximum≤ 40 %all year

How strict are these limits?

Cited limits by parameter: South Carolina'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/SC0039624 · MCP: https://passage-data.com/mcp