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City of Walnut

Sewage treatment plant, Walnut, Iowa. NPDES permit IA0042986 expired Apr 29, 2006; its limits still apply. Last 12 months: over a limit 7 times (last September 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 15 days after each period: form A monthly (24 values)
Last report on file
September 2026
Oct 2024 – Sep 2025
1 value over a limit, 0 required values missing, 0 of 12 reports late

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

Period endingParameterReportedLimitOver by
October 2025pH, daily maximum9.1≤ 9 SU—
November 2025BOD, carbonaceous [5 day, 20 C], 7-day average61≤ 40 mg/L53%
November 2025pH, daily maximum9.1≤ 9 SU—
December 2025pH, daily maximum9.1≤ 9 SU—
February 2026pH, daily maximum9.1≤ 9 SU—
September 2026Flow, in conduit or thru treatment plant, 30-day average.310806≤ .234 MGD33%
September 2026Flow, in conduit or thru treatment plant, daily maximum.514≤ .393 MGD31%

Limits in force (50)

ParameterStatisticLimitMonths
pHdaily minimum≥ 6 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≤ 80 mg/Lall year
Solids, total suspended7-day average≤ 120 mg/Lall year
Solids, total suspended30-day average≤ 156 lb/dall year
Solids, total suspended7-day average≤ 234 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, ammonia total [as N]30-day average≤ 8.7 mg/LAug
Nitrogen, ammonia total [as N]30-day average≤ 8.7 mg/LJul
Nitrogen, ammonia total [as N]daily maximum≤ 13 mg/LAug
Nitrogen, ammonia total [as N]daily maximum≤ 13 mg/LJul
Nitrogen, ammonia total [as N]30-day average≤ 13 lb/dSep
Nitrogen, ammonia total [as N]30-day average≤ 13 lb/dJun
Nitrogen, ammonia total [as N]30-day average≤ 13 lb/dMay
Nitrogen, ammonia total [as N]30-day average≤ 14 lb/dAug
Nitrogen, ammonia total [as N]30-day average≤ 14 lb/dJul
Nitrogen, ammonia total [as N]30-day average≤ 13 lb/dOct
Nitrogen, ammonia total [as N]30-day average≤ 13 lb/dNov
Nitrogen, ammonia total [as N]30-day average≤ 13 lb/dDec
Nitrogen, ammonia total [as N]30-day average≤ 13 lb/dApr
Nitrogen, ammonia total [as N]30-day average≤ 25 lb/dJan
Nitrogen, ammonia total [as N]30-day average≤ 13 lb/dMar
Nitrogen, ammonia total [as N]30-day average≤ 25 lb/dFeb
Nitrogen, ammonia total [as N]daily maximum≤ 21 lb/dSep
Nitrogen, ammonia total [as N]daily maximum≤ 21 lb/dJun
Nitrogen, ammonia total [as N]daily maximum≤ 21 lb/dMay
Nitrogen, ammonia total [as N]daily maximum≤ 24 lb/dAug
Nitrogen, ammonia total [as N]daily maximum≤ 24 lb/dJul
Nitrogen, ammonia total [as N]daily maximum≤ 21 lb/dOct
Nitrogen, ammonia total [as N]daily maximum≤ 21 lb/dNov
Nitrogen, ammonia total [as N]daily maximum≤ 21 lb/dDec
Nitrogen, ammonia total [as N]daily maximum≤ 21 lb/dApr
Nitrogen, ammonia total [as N]daily maximum≤ 42 lb/dJan
Nitrogen, ammonia total [as N]daily maximum≤ 21 lb/dMar
Nitrogen, ammonia total [as N]daily maximum≤ 42 lb/dFeb
Flow, in conduit or thru treatment plant30-day average≤ .234 MGDall year
Flow, in conduit or thru treatment plantdaily maximum≤ .393 MGDall 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≤ 49 lb/dall year
BOD, carbonaceous [5 day, 20 C]7-day average≤ 78 lb/dall year
BOD, carbonaceous [5 day, 20 C]30-day averagereport only (mg/L)all year
BOD, carbonaceous [5 day, 20 C]daily maximumreport only (mg/L)all year
BOD, carbonaceous [5 day, 20 C]30-day averagereport only (lb/d)all year
BOD, carbonaceous [5 day, 20 C]daily maximumreport only (lb/d)all year

How strict are these limits?

Cited limits by parameter: Iowa'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/IA0042986 · MCP: https://passage-data.com/mcp