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City of Colstrip

Sewage treatment plant, Colstrip, Montana. NPDES permit MT0022373 expired Oct 31, 2026. 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 (34 values), form Q quarterly (1 value)
Last report on file
August 2026
Oct 2024 – Sep 2025
0 values over a limit, 0 required values missing, 1 of 16 reports late

Limits in force (39)

ParameterStatisticLimitMonths
Temperature, water deg. centigrademonthly averagereport only (deg C)all year
Temperature, water deg. centigradedaily maximumreport only (deg C)all year
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≤ 150 lb/dall year
BOD, 5-day, 20 deg. Cmaximum weekly average≤ 225 lb/dall year
BOD, 5-day, 20 deg. Cmonthly averagereport only (mg/L)all year
BOD, 5-day, 20 deg. Cmaximum weekly averagereport only (mg/L)all year
pHminimum≥ 6 SUall year
pHmaximum≤ 9 SUall year
Solids, total suspendedmonthly average≤ 30 mg/Lall year
Solids, total suspendedmaximum weekly average≤ 45 mg/Lall year
Solids, total suspendedmonthly average≤ 150 lb/dall year
Solids, total suspendedmaximum weekly average≤ 225 lb/dall year
Solids, total suspendedmonthly averagereport only (mg/L)all year
Solids, total suspendedmaximum weekly averagereport only (mg/L)all year
Oil & Greasedaily maximum≤ 10 mg/Lall 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, ammonia total [as N]daily maximumreport only (mg/L)all year
Nitrogen, Kjeldahl, total [as N]monthly averagereport only (mg/L)all year
Nitrogen, Kjeldahl, total [as N]daily maximumreport only (mg/L)all year
Nitrite + Nitrate total [as N]monthly averagereport only (mg/L)Apr–Oct
Nitrite + Nitrate total [as N]monthly averagereport only (mg/L)Jan, Feb, Mar, Nov, Dec
Nitrite + Nitrate total [as N]daily maximumreport only (mg/L)Apr–Oct
Nitrite + Nitrate total [as N]daily maximum≤ 10 mg/LJan, Feb, Mar, Nov, Dec
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 meanreport only (#/100mL)Apr–Oct
E. coli, MTEC-MFmaximum weekly average≤ 1260 #/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFmaximum weekly averagereport only (#/100mL)Apr–Oct
BOD, 5-day, percent removalmonthly average minimum≥ 85 %all year
BOD, 5-day, percent removaldaily average≤ 85 %all year
Solids, suspended percent removalmonthly average minimum≥ 85 %all year
Solids, suspended percent removaldaily average≤ 85 %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/MT0022373 · MCP: https://passage-data.com/mcp