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Sewage treatment plant, Charlo, Montana. NPDES permit MT0022551, in force until Dec 31, 2030. Last 12 months: no values over a limit, 75 required values missing, 13 of 14 reports late. Source: EPA ECHO, Oct 22, 2026.
| Parameter | Statistic | Limit | Months | Outfall |
|---|---|---|---|---|
| Temperature, water deg. centigrade | 30-day average | report only (deg C) | all year | 001 |
| Temperature, water deg. centigrade | daily maximum | report only (deg C) | all year | 001 |
| Oxygen, dissolved [DO] | minimum | report only (mg/L) | all year | 001 |
| Oxygen, dissolved [DO] | 7-day average | report only (mg/L) | all year | 001 |
| BOD, 5-day, 20 deg. C | 30-day average | ≤ 30 mg/L | all year | 001 |
| BOD, 5-day, 20 deg. C | 7-day average | ≤ 45 mg/L | all year | 001 |
| pH | minimum | ≥ 6.5 SU | all year | 001 |
| pH | maximum | ≤ 8.5 SU | all year | 001 |
| Solids, total suspended | 30-day average | ≤ 30 mg/L | all year | 001 |
| Solids, total suspended | 7-day average | ≤ 45 mg/L | all year | 001 |
| Oil & Grease | maximum | ≤ 10 mg/L | all year | 001 |
| Nitrogen, total [as N] | average value | report only (mg/L) | May–Sep | 001 |
| Nitrogen, ammonia total [as N] | 30-day average | report only (mg/L) | all year | 001 |
| Nitrogen, ammonia total [as N] | daily maximum | report only (mg/L) | all year | 001 |
| Nitrite + Nitrate total [as N] | average value | report only (mg/L) | May–Sep | 001 |
| Phosphorus, total [as P] | average value | report only (mg/L) | May–Sep | 001 |
| E. coli | 30-day geometric mean | ≤ 126 #/100mL | all year | 001 |
| E. coli | daily maximum | ≤ 252 #/100mL | all year | 001 |
| Nitrogen, Kjeldahl Total | average value | report only (mg/L) | May–Sep | 001 |
| Date Discharge Began | value | report only (date) | all year | 001 |
| Flow rate | 30-day average | report only (gal/d) | all year | 001 |
| Flow rate | daily maximum | report only (gal/d) | all year | 001 |
| BOD, 5-day, percent removal | monthly average minimum | ≥ 85 % | all year | 001 |
| Solids, suspended percent removal | monthly average minimum | ≥ 85 % | all year | 001 |
| Duration of discharge | value | report only (d) | all year | 001 |
| Oil and grease visual | instantaneous maximum | ≤ 0 N=0;Y=1 | all year | 001 |
| BOD, 5-day, 20 deg. C | 30-day average | report only (mg/L) | all year | 001I |
| Solids, total suspended | 30-day average | report only (mg/L) | all year | 001I |
| Temperature, water deg. centigrade | average value | report only (deg C) | all year | RW01 |
| Oxygen, dissolved [DO] | average value | report only (mg/L) | all year | RW01 |
| pH | average value | report only (SU) | all year | RW01 |
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/MT0022551 · MCP: https://passage-data.com/mcp