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City of Malta

Sewage treatment plant, Malta, Montana. NPDES permit MT0020389 expired May 31, 2023; its limits still apply. Last 12 months: no values over a limit. Source: EPA ECHO, Oct 22, 2026.

Reports due
About 28 days after each period: form A monthly (26 values), form Q quarterly, form S twice a year
Last report on file
August 2026
Oct 2024 – Sep 2025
0 values over a limit, 0 required values missing, 4 of 18 reports late

Limits in force (38)

ParameterStatisticLimitMonths
Flow ratemonthly averagereport only (MGD)all year
Flow ratemonthly 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≤ 69 lb/dall year
BOD, 5-day, 20 deg. Cweekly average≤ 104 lb/dall year
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year
pHminimum≥ 6 SUall year
pHmaximum≤ 9 SUall year
Salinitysingle samplereport only (mg/L)all year
Solids, total suspendedmonthly average≤ 45 mg/Lall year
Solids, total suspendedweekly average≤ 65 mg/Lall year
Solids, total suspendedmonthly average≤ 104 lb/dall year
Solids, total suspendedweekly average≤ 150 lb/dall year
Solids, total suspendedmonthly averagereport only (mg/L)all year
Oil and grease, hexane extr methoddaily maximum≤ 10 mg/Lall year
Nitrogen, total [as N]90-day averagereport only (mg/L)all year
Nitrogen, total [as N]monthly averagereport only (mg/L)Jun–Sep
Nitrogen, total [as N]90-day averagereport only (lb/d)all year
Nitrogen, total [as N]monthly averagereport only (lb/d)Jun–Sep
Nitrogen, ammonia total [as N]monthly geometric mean≤ 1.3 mg/Lall year
Nitrogen, ammonia total [as N]maximum monthly geometric mean≤ 1.9 mg/Lall year
Nitrogen, Kjeldahl, total [as N]90-day averagereport only (mg/L)all year
Nitrite + Nitrate total [as N]90-day averagereport only (mg/L)all year
Phosphorus, total [as P]90-day averagereport only (mg/L)all year
Phosphorus, total [as P]monthly averagereport only (mg/L)Jun–Sep
Phosphorus, total [as P]90-day averagereport only (lb/d)all year
Phosphorus, total [as P]monthly averagereport only (lb/d)Jun–Sep
Chloride [as Cl]single samplereport only (mg/L)all year
E. coli, MTEC-MFmonthly geometric mean≤ 630 CFU/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFmonthly average≤ 126 CFU/100mLApr–Oct
E. coli, MTEC-MFmaximum monthly geometric mean≤ 1260 CFU/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFweekly average≤ 252 CFU/100mLApr–Oct
Chlorine, total residualmonthly averagereport only (mg/L)all year
Chlorine, total residualdaily maximum≤ .1 mg/Lall year
Solids, total dissolvedsingle 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.

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On EPA ECHO: Facility report · DMR history

Your permit document is the final word. As JSON: /api/v1/permits/MT0020389 · MCP: https://passage-data.com/mcp