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City of Harlowton

Sewage treatment plant, Harlowton, Montana. NPDES permit MT0020354, in force until Jan 31, 2028. Last 12 months: over a limit 11 times (last July 2026), 4 of 14 reports late. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: form A monthly (25 values), form S1 twice a year
Renewal application due
Aug 4, 2027 · 180 days before expiry; your permit may set another date
Last report on file
September 2026
Oct 2024 – Sep 2025
8 values over a limit, 11 required values missing, 12 of 14 reports late

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

Period endingParameterReportedLimitOver by
December 2025Solids, total suspended, monthly average46 mg/L≤ 45 mg/L2%
April 2026Solids, total suspended, monthly average53 mg/L≤ 45 mg/L18%
May 2026BOD, 5-day, 20 deg. C, monthly average32 mg/L≤ 30 mg/L7%
May 2026Solids, total suspended, monthly average73 mg/L≤ 45 mg/L62%
May 2026Solids, total suspended, maximum weekly average73 mg/L≤ 65 mg/L12%
June 2026Solids, total suspended, monthly average64 mg/L≤ 45 mg/L42%
July 2026BOD, 5-day, 20 deg. C, monthly average22 %≤ 30 mg/L—
July 2026BOD, 5-day, 20 deg. C, maximum weekly average22 %≤ 45 mg/L—
July 2026Solids, total suspended, monthly average102 mg/L≤ 45 mg/L127%
July 2026Solids, total suspended, monthly average85.07 lb/d≤ 82.6 lb/d3%
July 2026Solids, total suspended, maximum weekly average102 mg/L≤ 65 mg/L57%

Limits in force (28)

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≤ 55 lb/dall year
BOD, 5-day, 20 deg. Cmaximum weekly average≤ 82.6 lb/dall year
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year
pHdaily minimum≥ 6 SUall year
pHdaily maximum≤ 9 SUall year
Solids, total suspendedmonthly average≤ 45 mg/Lall year
Solids, total suspendedmaximum weekly average≤ 65 mg/Lall year
Solids, total suspendedmonthly average≤ 82.6 lb/dall year
Solids, total suspendedmaximum weekly average≤ 119.3 lb/dall year
Solids, total suspendedmonthly averagereport only (mg/L)all year
Oil & Greasemonthly averagereport only (mg/L)all year
Nitrogen, total [as N]monthly averagereport only (mg/L)Jul–Sep
Nitrogen, total [as N]monthly averagereport only (lb/d)Jul–Sep
Nitrogen, ammonia total [as N]monthly averagereport only (mg/L)all year
Nitrogen, Kjeldahl, total [as N]monthly averagereport only (mg/L)Jul–Sep
Nitrite + Nitrate total [as N]monthly averagereport only (mg/L)all year
Phosphorus, total [as P]monthly averagereport only (mg/L)Jul–Sep
Phosphorus, total [as P]monthly averagereport only (lb/d)Jul–Sep
E. coli, MTEC-MFmonthly geometric mean≤ 630 #/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFmonthly geometric mean≤ 126 #/100mLApr–Oct
E. coli, MTEC-MFmaximum weekly average≤ 1260 #/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFmaximum weekly average≤ 252 #/100mLApr–Oct
BOD, 5-day, percent removalminimum≥ 85 %all year
Solids, suspended percent removalminimum≥ 65 %all year

How strict are these limits?

Cited limits by parameter: Montana'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/MT0020354 · MCP: https://passage-data.com/mcp