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City of Shelby

Sewage treatment plant, Shelby, Montana. NPDES permit MT0031488 expired Feb 28, 2025; its limits still apply. Last 12 months: over a limit 6 times (last May 2026), 1 of 11 reports late. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: form A monthly (21 values)
Last report on file
August 2026
Oct 2024 – Sep 2025
10 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
May 2026BOD, 5-day, percent removal, monthly minimum70.6 %≥ 85 %96%
May 2026Solids, suspended percent removal, monthly minimum-3.1 %≥ 65 %195%
May 2026Solids, total suspended, daily maximum109 mg/L≤ 65 mg/L68%
May 2026Solids, total suspended, monthly average393 lb/d≤ 131 lb/d200%
May 2026Solids, total suspended, monthly average83.5 mg/L≤ 45 mg/L86%
May 2026Solids, total suspended, maximum weekly average546 lb/d≤ 189 lb/d189%

Limits in force (23)

ParameterStatisticLimitMonths
Flow ratemonthly averagereport only (MGD)all year
Flow ratedaily maximumreport only (MGD)all year
BOD, 5-day, 20 deg. Cmonthly average≤ 30 mg/Lall year
BOD, 5-day, 20 deg. Cmaximum weekly average≤ 45 mg/Lall year
BOD, 5-day, 20 deg. Cmonthly average≤ 87 lb/dall year
BOD, 5-day, 20 deg. Cmaximum weekly average≤ 131 lb/dall year
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year
pHdaily minimumreport only (SU)all year
pHdaily maximumreport only (SU)all year
Solids, total suspendedmonthly average≤ 45 mg/Lall year
Solids, total suspendeddaily maximum≤ 65 mg/Lall year
Solids, total suspendedmonthly average≤ 131 lb/dall year
Solids, total suspendedmaximum weekly average≤ 189 lb/dall year
Solids, total suspendedmonthly averagereport only (mg/L)all year
Oil & Greasedaily maximum≤ 10 mg/Lall year
E. coli, MTEC-MFmonthly geometric mean≤ 126 #/100mLApr–Oct
E. coli, MTEC-MFmonthly geometric mean≤ 630 #/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFdaily maximum≤ 252 #/100mLApr–Oct
E. coli, MTEC-MFmaximum weekly average≤ 1260 #/100mLJan, Feb, Mar, Nov, Dec
BOD, 5-day, percent removalmonthly minimum≥ 85 %all year
Solids, suspended percent removalmonthly minimum≥ 65 %all year
Duration of dischargetotalreport only (d)all year
Oil and grease visualvaluereport only (Y=0;N=1)all year

How strict are these limits?

Cited limits by parameter: Montana'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/MT0031488 · MCP: https://passage-data.com/mcp