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Bridge, Tunnel, & Elevated Highway, Mackinaw City, Michigan. NPDES permit MI0060278 expired Oct 1, 2025; its limits still apply. Last 12 months: no values over a limit. Source: EPA ECHO, Oct 22, 2026.
| Parameter | Statistic | Limit | Months | Outfall |
|---|---|---|---|---|
| Temperature, water deg. fahrenheit | daily maximum | report only (deg F) | all year | 001 |
| Temperature, water deg. fahrenheit | daily maximum | = 85 deg F | all year | 001 |
| Thermal Discharge | monthly average | = 57 MBTU/hr | Jan, Feb, Mar, Apr, May, Nov, Dec | 001 |
| Thermal Discharge | daily maximum | report only (MBTU/hr) | Jan, Feb, Mar, Apr, May, Nov, Dec | 001 |
| Flow rate | monthly average | report only (gal/min) | all year | 001 |
| Flow rate | daily maximum | report only (gal/min) | all year | 001 |
| Oxygen, dissolved [DO] | daily minimum | ≥ 4 mg/L | all year | 001 |
| pH | daily minimum | ≥ 6.5 SU | all year | 001 |
| pH | daily minimum | = 6.5 SU | all year | 001 |
| pH | daily maximum | ≤ 9 SU | all year | 001 |
| pH | daily maximum | = 9 SU | all year | 001 |
| Solids, total suspended | daily maximum | report only (mg/L) | all year | 001 |
| Solids, total suspended | monthly average | = 40 mg/L | all year | 001 |
| Solids, total suspended | daily maximum | report only (mg/L) | all year | 001 |
| Solids, total suspended | daily maximum | = 70 mg/L | all year | 001 |
| Solids, total suspended | daily maximum | ≤ 30 mg/L | all year | 001 |
| Oil & Grease | daily maximum | ≤ 15 mg/L | all year | 001 |
| Oil & Grease | daily maximum | = 15 mg/L | all year | 001 |
| Chloride [as Cl] | monthly average | report only (mg/L) | all year | 001 |
| Chloride [as Cl] | daily maximum | report only (mg/L) | all year | 001 |
| Equipment inspection - visual | value | report only (N=0;Y=1) | all year | 001 |
| Equipment inspection - visual | value | report only (N=0;Y=1) | all year | 001 |
| Flow, in conduit or thru treatment plant | monthly average | report only (MGD) | all year | 001 |
| Flow, in conduit or thru treatment plant | daily maximum | report only (MGD) | all year | 001 |
| Volume, total | daily maximum | report only (gal) | all year | 001 |
| Toxicity [acute], Ceriodaphnia dubia | daily maximum | = 1 tox acute | all year | 001 |
| Solids, total dissolved | monthly average | report only (mg/L) | all year | 001 |
| Solids, total dissolved | daily maximum | report only (mg/L) | all year | 001 |
| Outfall observation,visual, y/n response | value | report only (N=0;Y=1) | all year | 001 |
| Outfall observation,visual, y/n response | value | report only (N=0;Y=1) | all year | 001 |
| Toxic Units Static 24 Hr Acute Ceriodaphnia dubia | daily maximum | = 1 tox acute | all year | 001 |
| TU Static 24 Hr Acute Daphnia magna | daily maximum | = 1 tox acute | all year | 001 |
| TU Static 24 Hr Acute Pimephales promelas | daily maximum | = 1 tox acute | all year | 001 |
| pH | daily minimum | ≥ 6.5 SU | all year | 003 |
| pH | daily maximum | ≤ 9 SU | all year | 003 |
| Solids, total suspended | monthly average | ≤ 40 mg/L | all year | 003 |
| Solids, total suspended | daily maximum | ≤ 70 mg/L | all year | 003 |
| Oil & Grease | daily maximum | ≤ 15 mg/L | all year | 003 |
| Chloride [as Cl] | monthly average | report only (mg/L) | all year | 003 |
| Chloride [as Cl] | daily maximum | report only (mg/L) | all year | 003 |
| Equipment inspection - visual | value | report only (N=0;Y=1) | all year | 003 |
| Flow, in conduit or thru treatment plant | monthly average | report only (MGD) | all year | 003 |
| Flow, in conduit or thru treatment plant | daily maximum | report only (MGD) | all year | 003 |
| Toxicity [acute], Ceriodaphnia dubia | daily maximum | ≤ 1 tox acute | all year | 003 |
| Solids, total dissolved | monthly average | report only (mg/L) | all year | 003 |
| Solids, total dissolved | daily maximum | report only (mg/L) | all year | 003 |
| Outfall observation,visual, y/n response | value | report only (N=0;Y=1) | all year | 003 |
| Toxic Units Static 24 Hr Acute Ceriodaphnia dubia | daily maximum | ≤ 1 tox acute | all year | 003 |
| TU Static 24 Hr Acute Daphnia magna | daily maximum | ≤ 1 tox acute | all year | 003 |
| TU Static 24 Hr Acute Pimephales promelas | daily maximum | ≤ 1 tox acute | all year | 003 |
Cited limits by parameter: Michigan'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/MI0060278 · MCP: https://passage-data.com/mcp