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Butte Silver Bow City and County

Sewage treatment plant, major discharger, Butte, Montana. NPDES permit MT0022012 expired Mar 31, 2017; 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 (44 values), form Q quarterly (1 value), form W quarterly (2 values), form S twice a year
Last report on file
August 2026
Oct 2024 – Sep 2025
0 values over a limit, 0 required values missing, 2 of 22 reports late

Limits in force (59)

ParameterStatisticLimitMonths
Temperature, water deg. centigrademonthly averagereport only (deg C)all year
Temperature, water deg. centigradedaily maximumreport only (deg C)all year
Flow ratedaily averagereport only (MGD)all year
Flow ratedaily maximumreport only (MGD)all year
Flow ratedaily averagereport only (MGD)all year
Flow ratedaily maximumreport only (MGD)all year
Oxygen, dissolved [DO]monthly averagereport only (mg/L)all year
Oxygen, dissolved [DO]maximum weekly averagereport 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≤ 2127 lb/dall year
BOD, 5-day, 20 deg. Cmaximum weekly average≤ 3190 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
pHinstantaneous minimum≥ 6.5 SUall year
pHinstantaneous maximum≤ 9 SUall year
Solids, total suspendedmonthly average≤ 30 mg/Lall year
Solids, total suspendedmaximum weekly average≤ 45 mg/Lall year
Solids, total suspendedmonthly average≤ 2127 lb/dall year
Solids, total suspendedmaximum weekly average≤ 3190 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 average≤ 97 lb/dJun–Sep
Nitrogen, total [as N]monthly average≤ 136 lb/dJun–Sep
Nitrogen, ammonia total [as N]monthly average≤ 3.7 mg/Lall year
Nitrogen, ammonia total [as N]daily maximum≤ 7.5 mg/Lall year
Nitrogen, Kjeldahl, total [as N]monthly averagereport only (mg/L)Jun–Sep
Nitrogen, Kjeldahl, total [as N]weekly maximumreport only (mg/L)Jun–Sep
Nitrite + Nitrate total [as N]monthly averagereport only (mg/L)Jun–Sep
Nitrite + Nitrate total [as N]weekly maximumreport only (mg/L)Jun–Sep
Phosphorus, total [as P]monthly averagereport only (mg/L)Jun–Sep
Phosphorus, total [as P]monthly average≤ 13.6 lb/dJun–Sep
Phosphorus, total [as P]monthly average≤ 9.7 lb/dJun–Sep
Zinc, total recoverablemonthly average≤ 170 ug/Lall year
Zinc, total recoverablemonthly average≤ 122 ug/Lall year
Zinc, total recoverablemaximum≤ 234 ug/Lall year
Zinc, total recoverabledaily maximum≤ 151 ug/Lall year
Zinc, total recoverablesingle samplereport only (ug/L)all year
Cadmium, total recoverablemonthly average≤ .46 ug/Lall year
Cadmium, total recoverabledaily maximum≤ .67 ug/Lall year
Cadmium, total recoverablesingle samplereport only (ug/L)all year
Copper, total recoverablemonthly average≤ 12.8 ug/Lall year
Copper, total recoverablemonthly average≤ 14.4 ug/Lall year
Copper, total recoverabledaily maximum≤ 14 ug/Lall year
Copper, total recoverablemaximum≤ 28.9 ug/Lall year
Copper, total recoverablesingle samplereport only (ug/L)all year
E. coli, MTEC-MFmonthly average≤ 630 CFU/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFmonthly average≤ 126 CFU/100mLApr–Oct
E. coli, MTEC-MFmaximum weekly average≤ 1260 CFU/100mLJan, Feb, Mar, Nov, Dec
E. coli, MTEC-MFmaximum weekly average≤ 252 CFU/100mLApr–Oct
Solids, total dissolved [TDS]valuereport only (mg/L)all year
Mercury, total recoverablemonthly average≤ .025 ug/Lall year
Mercury, total recoverabledaily maximum≤ .05 ug/Lall year
Mercury, total recoverablesingle samplereport only (ug/L)all year
BOD, 5-day, percent removalminimum≥ 85 %all year
Solids, suspended percent removalminimum≥ 85 %all year
Pass/Fail Static 48Hr Acute Ceriodaphnia dubiasingle sample≤ 0 pass=0;fail=1all year
Pass/Fail Static Renewal 96Hr Acute Pimephales Promelassingle sample≤ 0 pass=0;fail=1all 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/MT0022012 · MCP: https://passage-data.com/mcp