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City of Red Oak

Sewage treatment plant, major discharger, Red Oak, Iowa. NPDES permit IA0040266, in force until Jan 31, 2030. Last 12 months: over a limit once (last March 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 15 days after each period: form A monthly (35 values)
Last report on file
August 2026
Oct 2024 – Sep 2025
4 values over a limit, 0 required values missing, 2 of 12 reports late

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

Period endingParameterReportedLimitOver by
March 2026Solids, total suspended, 7-day average58≤ 45 mg/L29%

Limits in force (79)

ParameterStatisticLimitMonths
BOD, 5-day, 20 deg. C30-day averagereport only (mg/L)all year
BOD, 5-day, 20 deg. Cdaily maximumreport only (mg/L)all year
BOD, 5-day, 20 deg. C30-day averagereport only (lb/d)all year
BOD, 5-day, 20 deg. Cdaily maximumreport only (lb/d)all year
pHdaily minimum≥ 6.5 SUall year
pHdaily maximum≤ 9 SUall year
pH30-day averagereport only (SU)all year
pHdaily maximumreport only (SU)all year
Solids, total suspended30-day average≤ 30 mg/Lall year
Solids, total suspended7-day average≤ 45 mg/Lall year
Solids, total suspended30-day average≤ 676 lb/dall year
Solids, total suspended7-day average≤ 1013 lb/dall year
Solids, total suspended30-day averagereport only (mg/L)all year
Solids, total suspendeddaily maximumreport only (mg/L)all year
Solids, total suspended30-day averagereport only (lb/d)all year
Solids, total suspendeddaily maximumreport only (lb/d)all year
Nitrogen, total [as N]30-day averagereport only (mg/L)all year
Nitrogen, total [as N]daily maximumreport only (mg/L)all year
Nitrogen, total [as N]30-day averagereport only (lb/d)all year
Nitrogen, total [as N]daily maximumreport only (lb/d)all year
Nitrogen, ammonia total [as N]30-day average≤ 7.5 mg/LMay
Nitrogen, ammonia total [as N]30-day average≤ 18.5 mg/LDec
Nitrogen, ammonia total [as N]30-day average≤ 11.7 mg/LOct
Nitrogen, ammonia total [as N]30-day average≤ 8.9 mg/LApr
Nitrogen, ammonia total [as N]30-day average≤ 12.5 mg/LMar
Nitrogen, ammonia total [as N]30-day average≤ 5.7 mg/LJul
Nitrogen, ammonia total [as N]30-day average≤ 5.6 mg/LSep
Nitrogen, ammonia total [as N]30-day average≤ 5.2 mg/LAug
Nitrogen, ammonia total [as N]30-day average≤ 15.7 mg/LNov
Nitrogen, ammonia total [as N]30-day average≤ 18.6 mg/LJan
Nitrogen, ammonia total [as N]30-day average≤ 4.9 mg/LJun
Nitrogen, ammonia total [as N]30-day average≤ 18.1 mg/LFeb
Nitrogen, ammonia total [as N]daily maximum≤ 17.4 mg/LMay
Nitrogen, ammonia total [as N]daily maximum≤ 18.5 mg/LDec
Nitrogen, ammonia total [as N]daily maximum≤ 18.2 mg/LOct
Nitrogen, ammonia total [as N]daily maximum≤ 17.9 mg/LApr
Nitrogen, ammonia total [as N]daily maximum≤ 17.6 mg/LMar
Nitrogen, ammonia total [as N]daily maximum≤ 20.1 mg/LJul
Nitrogen, ammonia total [as N]daily maximum≤ 19.1 mg/LSep
Nitrogen, ammonia total [as N]daily maximum≤ 18.4 mg/LAug
Nitrogen, ammonia total [as N]daily maximum≤ 16.8 mg/LNov
Nitrogen, ammonia total [as N]daily maximum≤ 18.6 mg/LJan
Nitrogen, ammonia total [as N]daily maximum≤ 16.6 mg/LJun
Nitrogen, ammonia total [as N]daily maximum≤ 18.1 mg/LFeb
Nitrogen, ammonia total [as N]30-day average≤ 80.8 lb/dMay
Nitrogen, ammonia total [as N]30-day average≤ 169.1 lb/dDec
Nitrogen, ammonia total [as N]30-day average≤ 106.2 lb/dOct
Nitrogen, ammonia total [as N]30-day average≤ 94.6 lb/dApr
Nitrogen, ammonia total [as N]30-day average≤ 131.1 lb/dMar
Nitrogen, ammonia total [as N]30-day average≤ 56.4 lb/dJul
Nitrogen, ammonia total [as N]30-day average≤ 62.5 lb/dSep
Nitrogen, ammonia total [as N]30-day average≤ 51.4 lb/dAug
Nitrogen, ammonia total [as N]30-day average≤ 158.9 lb/dNov
Nitrogen, ammonia total [as N]30-day average≤ 233.6 lb/dJan
Nitrogen, ammonia total [as N]30-day average≤ 55.4 lb/dJun
Nitrogen, ammonia total [as N]30-day average≤ 268.5 lb/dFeb
Nitrogen, ammonia total [as N]daily maximum≤ 357.5 lb/dMay
Nitrogen, ammonia total [as N]daily maximum≤ 377.6 lb/dDec
Nitrogen, ammonia total [as N]daily maximum≤ 371.5 lb/dOct
Nitrogen, ammonia total [as N]daily maximum≤ 369.4 lb/dApr
Nitrogen, ammonia total [as N]daily maximum≤ 351 lb/dMar
Nitrogen, ammonia total [as N]daily maximum≤ 414.1 lb/dJul
Nitrogen, ammonia total [as N]daily maximum≤ 389.8 lb/dSep
Nitrogen, ammonia total [as N]daily maximum≤ 380.9 lb/dAug
Nitrogen, ammonia total [as N]daily maximum≤ 345.9 lb/dNov
Nitrogen, ammonia total [as N]daily maximum≤ 365.9 lb/dJan
Nitrogen, ammonia total [as N]daily maximum≤ 340.3 lb/dJun
Nitrogen, ammonia total [as N]daily maximum≤ 347.6 lb/dFeb
Nitrogen, Kjeldahl, total [as N]30-day averagereport only (mg/L)all year
Nitrogen, Kjeldahl, total [as N]daily maximumreport only (mg/L)all year
Nitrogen, Kjeldahl, total [as N]30-day averagereport only (lb/d)all year
Nitrogen, Kjeldahl, total [as N]daily maximumreport only (lb/d)all year
E. coligeometric mean≤ 126 #/100mLMar–Nov
Toxicity [acute], Ceriodaphnia dubiadaily maximum≤ 1 N=0;Y=1all year
Toxicity [acute], Pimephales promelas [Fathead Minnow]daily maximum≤ 1 N=0;Y=1all year
BOD, carbonaceous [5 day, 20 C]30-day average≤ 25 mg/Lall year
BOD, carbonaceous [5 day, 20 C]7-day average≤ 40 mg/Lall year
BOD, carbonaceous [5 day, 20 C]30-day average≤ 563 lb/dall year
BOD, carbonaceous [5 day, 20 C]7-day average≤ 901 lb/dall year

How strict are these limits?

Cited limits by parameter: Iowa'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/IA0040266 · MCP: https://passage-data.com/mcp