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Town of Culbertson

Sewage treatment plant, Culbertson, Montana. NPDES permit MT0031798, in force until Nov 30, 2026. Last 12 months: over a limit 18 times (last June 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: form A monthly (23 values), form Q quarterly (2 values)
Renewal application due
Jun 3, 2026 · 180 days before expiry; your permit may set another date
Last report on file
September 2026
Oct 2024 – Sep 2025
15 values over a limit, 0 required values missing, 0 of 16 reports late

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

All 18 values over a limit
Period endingParameterReportedLimitOver by
October 2025pH, instantaneous maximum9.3 SU≤ 9 SU—
November 2025pH, instantaneous maximum9.2 SU≤ 9 SU—
December 2025pH, instantaneous maximum9.2 SU≤ 9 SU—
January 2026pH, instantaneous maximum9.2 SU≤ 9 SU—
February 2026pH, instantaneous maximum9.2 SU≤ 9 SU—
March 2026pH, instantaneous maximum9.4 SU≤ 9 SU—
April 2026BOD, 5-day, 20 deg. C, monthly average37 mg/L≤ 30 mg/L23%
April 2026Solids, suspended percent removal, minimum69.6 %≥ 85 %103%
April 2026Solids, total suspended, monthly average55 mg/L≤ 30 mg/L83%
April 2026Solids, total suspended, weekly average55 mg/L≤ 45 mg/L22%
April 2026pH, instantaneous maximum9.9 SU≤ 9 SU—
May 2026Solids, suspended percent removal, minimum53.8 %≥ 85 %208%
May 2026Solids, total suspended, monthly average79 mg/L≤ 30 mg/L163%
May 2026Solids, total suspended, weekly average79 mg/L≤ 45 mg/L76%
May 2026pH, instantaneous maximum9.6 SU≤ 9 SU—
June 2026Solids, suspended percent removal, minimum71.58 %≥ 85 %89%
June 2026Solids, total suspended, monthly average52 mg/L≤ 30 mg/L73%
June 2026Solids, total suspended, weekly average52 mg/L≤ 45 mg/L16%

Limits in force (25)

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. Cweekly average≤ 45 mg/Lall year
BOD, 5-day, 20 deg. Cmonthly average≤ 50 lb/dall year
BOD, 5-day, 20 deg. Cweekly average≤ 75 lb/dall year
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year
BOD, 5-day, 20 deg. Cweekly averagereport only (mg/L)all year
pHinstantaneous minimum≥ 6 SUall year
pHinstantaneous maximum≤ 9 SUall year
Solids, total suspendedmonthly average≤ 30 mg/Lall year
Solids, total suspendedweekly average≤ 45 mg/Lall year
Solids, total suspendedmonthly average≤ 50 lb/dall year
Solids, total suspendedweekly average≤ 75 lb/dall year
Solids, total suspendedmonthly averagereport only (mg/L)all year
Solids, total suspendedweekly averagereport only (mg/L)all year
Oil and grease, hexane extr methodsingle grab samplereport only (mg/L)all year
Nitrogen, total [as N]monthly averagereport only (mg/L)Aug–Oct
Nitrogen, ammonia total [as N]single grab samplereport only (mg/L)all year
Nitrogen, Kjeldahl, total [as N]single grab samplereport only (mg/L)Aug–Oct
Nitrite + Nitrate total [as N]single grab samplereport only (mg/L)Aug–Oct
Phosphorus, total [as P]single grab samplereport only (mg/L)Aug–Oct
E. coli, MTEC-MFmonthly averagereport only (CFU/100mL)all year
BOD, 5-day, percent removalminimum≥ 85 %all year
Solids, suspended percent removalminimum≥ 85 %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/MT0031798 · MCP: https://passage-data.com/mcp