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Utilities, COLUMBIA CITY OF

Sewage treatment plant, major discharger, Columbia, South Carolina. NPDES permit SC0020940 expired May 31, 2023; its limits still apply. Last 12 months: over a limit 5 times (last June 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 29 days after each period: form 1 monthly (33 values), form 2 quarterly, form 3 yearly, form 4 twice a year
Last report on file
August 2026
Oct 2024 – Sep 2025
1 value over a limit, 0 required values missing, 0 of 19 reports late

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

Period endingParameterReportedLimitOver by
May 2026E. coli, daily maximum411≤ 349 MPN/100mL18%
June 2026Chlorine, total residual, daily maximum> 2.2≤ .17 mg/L—
June 2026Chlorine, total residual, daily maximum> 477.36≤ 85.07 lb/d—
June 2026Chlorine, total residual, monthly average> .11≤ .1 mg/L—
June 2026Chlorine, total residual, monthly average> 23.87≤ 50.04 lb/d—

Limits in force (57)

ParameterStatisticLimitMonths
Oxygen demand, ultimatemonthly average≤ 38163 lb/dMar–Oct
Oxygen demand, ultimatemonthly average≤ 57914 lb/dJan, Feb, Nov, Dec
Oxygen demand, ultimateweekly average≤ 57244 lb/dMar–Oct
Oxygen demand, ultimateweekly average≤ 86871 lb/dJan, Feb, Nov, Dec
Oxygen, dissolved [DO]minimum≥ 5 mg/Lall year
BOD, 5-day, 20 deg. Cmonthly average≤ 30 mg/LMar–Oct
BOD, 5-day, 20 deg. Cmonthly average≤ 30 mg/LJan, Feb, Nov, Dec
BOD, 5-day, 20 deg. Cweekly average≤ 45 mg/LMar–Oct
BOD, 5-day, 20 deg. Cweekly average≤ 45 mg/LJan, Feb, Nov, Dec
BOD, 5-day, 20 deg. Cmonthly average≤ 15012 lb/dMar–Oct
BOD, 5-day, 20 deg. Cmonthly average≤ 15012 lb/dJan, Feb, Nov, Dec
BOD, 5-day, 20 deg. Cweekly average≤ 22518 lb/dMar–Oct
BOD, 5-day, 20 deg. Cweekly average≤ 22518 lb/dJan, Feb, Nov, Dec
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≤ 15012 lb/dall year
Solids, total suspendedweekly average≤ 22518 lb/dall year
Nitrogen, total [as N]monthly averagereport only (mg/L)all year
Nitrogen, total [as N]weekly averagereport only (mg/L)all year
Nitrogen, total [as N]monthly averagereport only (lb/d)all year
Nitrogen, total [as N]weekly averagereport only (lb/d)all year
Nitrogen, ammonia total [as N]monthly average≤ 13.93 mg/LMar–Oct
Nitrogen, ammonia total [as N]monthly average≤ 20 mg/LJan, Feb, Nov, Dec
Nitrogen, ammonia total [as N]weekly average≤ 20.89 mg/LMar–Oct
Nitrogen, ammonia total [as N]weekly average≤ 30 mg/LJan, Feb, Nov, Dec
Nitrogen, ammonia total [as N]monthly average≤ 6971 lb/dMar–Oct
Nitrogen, ammonia total [as N]monthly average≤ 10008 lb/dJan, Feb, Nov, Dec
Nitrogen, ammonia total [as N]weekly average≤ 10453 lb/dMar–Oct
Nitrogen, ammonia total [as N]weekly average≤ 15012 lb/dJan, Feb, Nov, Dec
Phosphorus, total [as P]monthly averagereport only (mg/L)all year
Phosphorus, total [as P]weekly averagereport only (mg/L)all year
Phosphorus, total [as P]monthly averagereport only (lb/d)all year
Phosphorus, total [as P]weekly averagereport only (lb/d)all year
Copper, total [as Cu]monthly averagereport only (mg/L)all year
Copper, total [as Cu]daily maximumreport only (mg/L)all year
Copper, total [as Cu]monthly averagereport only (lb/d)all year
Copper, total [as Cu]daily maximumreport 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≤ .1 mg/Lall year
Chlorine, total residualdaily maximum≤ .17 mg/Lall year
Chlorine, total residualmonthly average≤ 50.04 lb/dall year
Chlorine, total residualdaily maximum≤ 85.07 lb/dall year
E. coli30-day geometric mean≤ 126 MPN/100mLall year
E. colidaily maximum≤ 349 MPN/100mLall year
E. coli30-day geometric mean≤ 126 MPN/100mLall year
E. colidaily maximum≤ 800 MPN/100mLall year
Mercury, total [as Hg]monthly averagereport only (ng/L)all year
Mercury, total [as Hg]daily maximumreport only (ng/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
BOD, 5-day, percent removalmonthly average minimum≥ 85 %all year
Solids, suspended percent removalmonthly average minimum≥ 85 %all 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.

Check this month's numbers Email me before each report is due

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On EPA ECHO: Facility report · DMR history

Your permit document is the final word. As JSON: /api/v1/permits/SC0020940 · MCP: https://passage-data.com/mcp