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Yankton, City of

Sewage treatment plant, major discharger, Yankton, South Dakota. NPDES permit SD0023396 expired Mar 31, 2026; its limits still apply. Last 12 months: over a limit 6 times (last September 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 29 days after each period: form A monthly (31 values), form W quarterly (2 values), form ME yearly, form MI yearly, form T every 59 months
Last report on file
September 2026
Oct 2024 – Sep 2025
0 values over a limit, 4 required values missing, 3 of 18 reports late

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

Period endingParameterReportedLimitOver by
January 2026Coliform, total general, daily maximum20001 #/100mL≤ 20000 #/100mL0%
August 2026E. coli, colony forming units [CFU], daily maximum1020 #/100mL≤ 235 #/100mL334%
August 2026Solids, suspended percent removal, monthly average minimum83 %≥ 85 %13%
August 2026Solids, total suspended, 30-day average39 mg/L≤ 30 mg/L30%
August 2026Solids, total suspended, maximum 7-day average78.6 mg/L≤ 45 mg/L75%
September 2026Toxicity [acute], Pimephales promelas [Fathead Minnow], daily maximum1.8 tox acute≤ 1 tox acute80%

Limits in force (72)

ParameterStatisticLimitMonths
Temperature, water deg. centigrade30-day averagereport only (deg C)all year
Temperature, water deg. centigradedaily maximumreport only (deg C)all year
Flow rate30-day averagereport only (MGD)all year
Flow ratedaily maximumreport only (MGD)all year
Oxygen, dissolved [DO]daily minimumreport only (mg/L)all year
Oxygen, dissolved [DO]30-day averagereport only (mg/L)all year
BOD, 5-day, 20 deg. C30-day average≤ 30 mg/Lall year
BOD, 5-day, 20 deg. Cmaximum 7-day average≤ 45 mg/Lall year
BOD, 5-day, 20 deg. C30-day averagereport only (mg/L)all year
pHdaily minimum≥ 6.5 SUall year
pHdaily maximum≤ 8.3 SUall year
Solids, total suspended30-day average≤ 30 mg/Lall year
Solids, total suspendedmaximum 7-day average≤ 45 mg/Lall year
Solids, total suspended30-day averagereport only (mg/L)all year
Oil and grease, hexane extr methoddaily maximum≤ 1 mg/Lall year
Nitrogen, total [as N]daily maximumreport only (mg/L)all year
Nitrogen, ammonia total [as N]30-day averagereport only (mg/L)all year
Nitrogen, ammonia total [as N]daily maximumreport only (mg/L)all year
Nitrogen, nitrate total [as N]daily maximumreport only (mg/L)all year
Phosphorus, total [as P]daily maximumreport only (mg/L)all year
Cyanide, weak acid, dissociabledaily maximumreport only (ug/L)all year
Cyanide, weak acid, dissociabledaily maximumreport only (ug/L)all year
Cyanide, total [as CN]daily maximumreport only (ug/L)all year
Cyanide, total [as CN]daily maximumreport only (ug/L)all year
Hardness, total [as CaCO3]daily maximumreport only (mg/L)all year
Hardness, total [as CaCO3]daily maximumreport only (mg/L)all year
Arsenic, total recoverabledaily maximumreport only (ug/L)all year
Arsenic, total recoverabledaily maximumreport only (ug/L)all year
Selenium, total recoverabledaily maximumreport only (ug/L)all year
Selenium, total recoverabledaily maximumreport only (ug/L)all year
Thallium, total recoverabledaily maximumreport only (ug/L)all year
Thallium, total recoverabledaily maximumreport only (ug/L)all year
Selenite, Total Recoverabledaily maximumreport only (ug/L)all year
Beryllium, total recoverable [as Be]daily maximumreport only (ug/L)all year
Beryllium, total recoverable [as Be]daily maximumreport only (ug/L)all year
Nickel, total recoverabledaily maximumreport only (ug/L)all year
Nickel, total recoverabledaily maximumreport only (ug/L)all year
Silver total recoverabledaily maximumreport only (ug/L)all year
Silver total recoverabledaily maximumreport only (ug/L)all year
Zinc, total recoverabledaily maximumreport only (ug/L)all year
Zinc, total recoverabledaily maximumreport only (ug/L)all year
Cadmium, total recoverabledaily maximumreport only (ug/L)all year
Cadmium, total recoverabledaily maximumreport only (ug/L)all year
Lead, total recoverabledaily maximumreport only (ug/L)all year
Lead, total recoverabledaily maximumreport only (ug/L)all year
Chromium, total recoverabledaily maximumreport only (ug/L)all year
Chromium, total recoverabledaily maximumreport only (ug/L)all year
Copper, total recoverabledaily maximumreport only (ug/L)all year
Copper, total recoverabledaily maximumreport only (ug/L)all year
Molybdenum, total recoverabledaily maximumreport only (ug/L)all year
Molybdenum, total recoverabledaily maximumreport only (ug/L)all year
Antimony, total recoverabledaily maximumreport only (ug/L)all year
Antimony, total recoverabledaily maximumreport only (ug/L)all year
Phenolsdaily maximumreport only (ug/L)all year
Phenolsdaily maximumreport only (ug/L)all year
E. coli, colony forming units [CFU]30-day geometric mean≤ 126 #/100mLMay–Sep
E. coli, colony forming units [CFU]daily maximum≤ 235 #/100mLMay–Sep
Selenate, Total Recoverabledaily maximumreport only (ug/L)all year
Toxicity [acute], Ceriodaphnia dubiadaily maximum≤ 1 tox acuteall year
Toxicity [acute], Pimephales promelas [Fathead Minnow]daily maximum≤ 1 tox acuteall year
Mercury, total [as Hg]annual maximum≤ 1.4 ug/Lall year
Mercury, total recoverabledaily maximumreport only (ug/L)all year
Mercury, total recoverabledaily maximum≤ 1.4 ug/Lall year
Coliform, total general30-day geometric mean≤ 5000 #/100mLall year
Coliform, total generaldaily maximum≤ 20000 #/100mLall year
BOD, 5-day, percent removalmonthly average minimum≥ 85 %all year
Solids, suspended percent removalmonthly average minimum≥ 85 %all year
Oil and grease visualdaily maximum≤ 0 abst=0;prst=1all year
Report due [yrmoda]value≤ 0 Y=0;N=1all year
Report due [yrmoda]value≤ 0 Y=0;N=1all year
Report due [yrmoda]value≤ 0 Y=0;N=1all year
Report due [yrmoda]value≤ 0 Y=0;N=1all year

How strict are these limits?

Cited limits by parameter: South Dakota'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/SD0023396 · MCP: https://passage-data.com/mcp