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Primary Nonferrous Metals, Silver Bow, Montana. NPDES permit MT0030350 expired Jul 31, 2026; its limits still apply. Last 12 months: over a limit 3 times (last August 2026). Source: EPA ECHO, Oct 22, 2026.
| Period ending | Parameter | Reported | Limit | Over by |
|---|---|---|---|---|
| July 2026 | Aluminum, dissolved [as Al], monthly average | 99.75 ug/L | ≤ 68 ug/L | 47% |
| July 2026 | Nitrogen, total [as N], monthly average | < 2.39 lb/d | ≤ 2.15 lb/d | 11% |
| August 2026 | Nitrogen, total [as N], monthly average | < 2.29 lb/d | ≤ 2.15 lb/d | 7% |
| Parameter | Statistic | Limit | Months | Outfall |
|---|---|---|---|---|
| Flow rate | monthly average | report only (MGD) | all year | 001 |
| Flow rate | daily maximum | report only (MGD) | all year | 001 |
| Oxygen, dissolved [DO] | daily minimum | ≥ 4 mg/L | all year | 001 |
| Oxygen, dissolved [DO] | monthly average minimum | ≥ 6.5 mg/L | all year | 001 |
| pH | instantaneous minimum | ≥ 6 SU | all year | 001 |
| pH | instantaneous maximum | ≤ 9 SU | all year | 001 |
| Oil & Grease | maximum | ≤ 10 mg/L | all year | 001 |
| Nitrogen, total [as N] | monthly average | report only (mg/L) | Jun–Sep | 001 |
| Nitrogen, total [as N] | monthly average | ≤ 2.15 lb/d | Jun–Sep | 001 |
| Nitrogen, Kjeldahl, total [as N] | monthly average | report only (mg/L) | Jun–Sep | 001 |
| Nitrite + Nitrate total [as N] | monthly average | report only (mg/L) | Jun–Sep | 001 |
| Phosphorus, total [as P] | monthly average | report only (mg/L) | Jun–Sep | 001 |
| Phosphorus, total [as P] | monthly average | ≤ .243 lb/d | Jun–Sep | 001 |
| Arsenic, total recoverable | monthly average | ≤ 10 ug/L | all year | 001 |
| Arsenic, total recoverable | daily maximum | ≤ 10 ug/L | all year | 001 |
| Nickel, total recoverable | monthly average | ≤ 100 ug/L | all year | 001 |
| Nickel, total recoverable | daily maximum | ≤ 100 ug/L | all year | 001 |
| Zinc, total recoverable | monthly average | ≤ 102 ug/L | all year | 001 |
| Zinc, total recoverable | daily maximum | ≤ 180 ug/L | all year | 001 |
| Aluminum, dissolved [as Al] | monthly average | ≤ 68 ug/L | all year | 001 |
| Aluminum, dissolved [as Al] | daily maximum | ≤ 153 ug/L | all year | 001 |
| Copper, total recoverable | monthly average | ≤ 9.8 ug/L | all year | 001 |
| Copper, total recoverable | daily maximum | ≤ 22.5 ug/L | all year | 001 |
| Chlorine, total residual | monthly average | ≤ .0999 mg/L | all year | 001 |
| Chlorine, total residual | daily maximum | ≤ .0999 mg/L | all year | 001 |
| Solids, total dissolved [TDS] | monthly average | ≤ 1000 mg/L | all year | 001 |
| Mercury, total recoverable | monthly average | ≤ .05 ug/L | all year | 001 |
| Mercury, total recoverable | daily maximum | ≤ .05 ug/L | all year | 001 |
| Oil and grease visual | value | report only (Y=0;N=1) | all year | 001 |
| Pass/Fail Static Renewal 7 Day Chronic Ceriodaphnia dubia | value | ≤ 0 pass=0;fail=1 | all year | 001 |
| Pass/Fail Static Renewal 7Day Chronic Pimephales promelas | value | ≤ 0 pass=0;fail=1 | all year | 001 |
| Flow rate | monthly average | report only (MGD) | all year | 001B |
| Flow rate | daily maximum | report only (MGD) | all year | 001B |
| BOD, 5-day, 20 deg. C | monthly average | ≤ 30 mg/L | all year | 001B |
| BOD, 5-day, 20 deg. C | daily maximum | ≤ 45 mg/L | all year | 001B |
| Solids, total suspended | monthly average | ≤ 30 mg/L | all year | 001B |
| Solids, total suspended | daily maximum | ≤ 100 mg/L | all year | 001B |
| Chemical Oxygen Demand [COD] | monthly average | ≤ 120 mg/L | all year | 001B |
| Chemical Oxygen Demand [COD] | daily maximum | ≤ 180 mg/L | all year | 001B |
| Flow rate | daily maximum | report only (MGD) | all year | 002 |
| Solids, total suspended | daily maximum | report only (mg/L) | all year | 002 |
| Arsenic, total recoverable | daily maximum | report only (ug/L) | all year | 002 |
| Zinc, total recoverable | daily maximum | report only (ug/L) | all year | 002 |
| Lead, total recoverable | daily maximum | report only (ug/L) | all year | 002 |
| Copper, total recoverable | daily maximum | report only (ug/L) | all year | 002 |
| Chemical Oxygen Demand [COD] | daily maximum | report only (mg/L) | all year | 002 |
| Oil and grease visual | value | report only (Y=0;N=1) | all year | 002 |
| Flow rate | monthly average | report only (MGD) | all year | 003 |
| Flow rate | daily maximum | report only (MGD) | all year | 003 |
| Oxygen, dissolved [DO] | daily minimum | ≥ 6 mg/L | all year | 003 |
| Oxygen, dissolved [DO] | weekly geometric mean | ≤ 5 mg/L | all year | 003 |
| pH | instantaneous minimum | ≥ 6 SU | all year | 003 |
| pH | instantaneous maximum | ≤ 9 SU | all year | 003 |
| Oil & Grease | maximum | ≤ 10 mg/L | all year | 003 |
| Nitrogen, total [as N] | monthly average | report only (mg/L) | Jun–Sep | 003 |
| Nitrogen, total [as N] | monthly average | ≤ 2.15 lb/d | Jun–Sep | 003 |
| Nitrogen, Kjeldahl, total [as N] | monthly average | report only (mg/L) | Jun–Sep | 003 |
| Nitrite + Nitrate total [as N] | monthly average | report only (mg/L) | Jun–Sep | 003 |
| Phosphorus, total [as P] | monthly average | report only (mg/L) | Jun–Sep | 003 |
| Phosphorus, total [as P] | monthly average | ≤ .243 lb/d | Jun–Sep | 003 |
| Arsenic, total recoverable | monthly average | ≤ 10 ug/L | all year | 003 |
| Arsenic, total recoverable | daily maximum | ≤ 10 ug/L | all year | 003 |
| Nickel, total recoverable | monthly average | ≤ 75 ug/L | all year | 003 |
| Nickel, total recoverable | daily maximum | ≤ 93 ug/L | all year | 003 |
| Zinc, total recoverable | monthly average | ≤ 102 ug/L | all year | 003 |
| Zinc, total recoverable | daily maximum | ≤ 180 ug/L | all year | 003 |
| Aluminum, dissolved [as Al] | monthly average | ≤ 68 ug/L | all year | 003 |
| Aluminum, dissolved [as Al] | daily maximum | ≤ 153 ug/L | all year | 003 |
| Copper, total recoverable | monthly average | ≤ 9.8 ug/L | all year | 003 |
| Copper, total recoverable | daily maximum | ≤ 22.5 ug/L | all year | 003 |
| Chlorine, total residual | monthly average | ≤ .0999 mg/L | all year | 003 |
| Chlorine, total residual | daily maximum | ≤ .0999 mg/L | all year | 003 |
| Solids, total dissolved [TDS] | monthly average | ≤ 1000 mg/L | all year | 003 |
| Mercury, total recoverable | monthly average | ≤ .05 ug/L | all year | 003 |
| Mercury, total recoverable | daily maximum | ≤ .05 ug/L | all year | 003 |
| Pass/Fail Static Renewal 7 Day Chronic Ceriodaphnia dubia | value | ≤ 0 pass=0;fail=1 | all year | 003 |
| Pass/Fail Static Renewal 7Day Chronic Pimephales promelas | value | ≤ 0 pass=0;fail=1 | all year | 003 |
Cited limits by parameter: Montana's rules and the federal ones.
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Your permit document is the final word. As JSON: /api/v1/permits/MT0030350 · MCP: https://passage-data.com/mcp