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Town of Ennis

Sewage treatment plant, Ennis, Montana. NPDES permit MT0030732 expired Apr 30, 2019; its limits still apply. Last 12 months: over a limit 4 times (last May 2026). Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: form A monthly (33 values), form QM quarterly (4 values), form UP quarterly (3 values), form S twice a year
Last report on file
August 2026
Oct 2024 – Sep 2025
1 value over a limit, 0 required values missing, 2 of 22 reports late

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

Period endingParameterReportedLimitOver by
March 2026BOD, 5-day, 20 deg. C, monthly average29.1 lb/d≤ 25 lb/d16%
March 2026BOD, 5-day, 20 deg. C, monthly average38 mg/L≤ 30 mg/L27%
May 2026BOD, 5-day, 20 deg. C, monthly average26 lb/d≤ 25 lb/d4%
May 2026BOD, 5-day, 20 deg. C, monthly average34 mg/L≤ 30 mg/L13%

Limits in force (44)

ParameterStatisticLimitMonths
Temperature, water deg. centigrademonthly averagereport only (deg C)all year
Temperature, water deg. centigradesingle samplereport only (deg C)all year
Flow ratemonthly averagereport only (MGD)all year
Flow ratedaily maximumreport only (MGD)all year
Flow ratemonthly averagereport only (MGD)all year
Flow ratedaily maximumreport only (MGD)all year
Oxygen, dissolved [DO]single grab samplereport only (mg/L)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≤ 25 lb/dall year
BOD, 5-day, 20 deg. Cmaximum weekly average≤ 90 lb/dall year
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year
pHinstantaneous minimum≥ 6 SUall year
pHsingle samplereport only (SU)all year
pHinstantaneous 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≤ 85 lb/dall year
Solids, total suspendedmaximum weekly average≤ 130 lb/dall year
Solids, total suspendedmonthly 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 (ug/L)Jul–Sep
Nitrogen, total [as N]maximum weekly averagereport only (ug/L)Jul–Sep
Nitrogen, total [as N]monthly averagereport only (lb/d)Jul–Sep
Nitrogen, total [as N]maximum weekly averagereport only (lb/d)Jul–Sep
Nitrogen, ammonia total [as N]monthly average≤ 30 mg/Lall year
Nitrogen, ammonia total [as N]single grab samplereport only (mg/L)all year
Nitrogen, ammonia total [as N]daily maximum≤ 42 mg/Lall year
Nitrogen, Kjeldahl, total [as N]monthly averagereport only (mg/L)Jul–Sep
Nitrite + Nitrate total [as N]monthly averagereport only (mg/L)Jul–Sep
Phosphorus, total [as P]monthly averagereport only (mg/L)Jul–Sep
Phosphorus, total [as P]minimum weekly averagereport only (mg/L)Jul–Sep
Phosphorus, total [as P]monthly averagereport only (lb/d)Jul–Sep
Phosphorus, total [as P]maximum weekly averagereport only (lb/d)Jul–Sep
Arsenic, total recoverablesingle grab samplereport only (ug/L)all year
Zinc, total recoverablesingle grab samplereport only (ug/L)all year
Copper, total recoverablesingle grab samplereport only (ug/L)all year
E. coli, MTEC-MFmonthly average≤ 126 CFU/100mLApr–Oct
E. coli, MTEC-MFmonthly average≤ 630 CFU/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFmaximum weekly average≤ 252 CFU/100mLApr–Oct
E. coli, MTEC-MFmaximum weekly average≤ 1260 CFU/100mLJan, Feb, Mar, Nov, Dec
Solids, total dissolved [TDS]single grab samplereport only (mg/L)all year
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/MT0030732 · MCP: https://passage-data.com/mcp