Mackinac Island STP - Wastewater Treatment Plant in Mackinac Island, Michigan

Mackinac Island STP is a municipal wastewater treatment facility located on Mackinac Island in Michigan, United States. The plant serves a small population of approximately 473 residents, reflecting the island's year-round community. As a facility in a remote island setting, it plays a crucial role in protecting the pristine environment of the region. The plant operates under the US Clean Water Act, which requires National Pollutant Discharge Elimination System (NPDES) permits for all discharges. For small communities like Mackinac Island, treatment typically involves secondary treatment or equivalent to meet water quality standards. The plant's designed capacity is 1.00 million gallons per day, indicating it is sized to handle seasonal tourist population increases. The treated effluent is discharged into the Straits of Mackinac, a vital waterway connecting Lake Michigan and Lake Huron. This area supports diverse aquatic life and is an important corridor for fish migration. The plant's operations are critical to maintaining water quality in the Great Lakes ecosystem, which provides drinking water and recreational opportunities for millions.

The plant discharges into the Straits of Mackinac, which connects Lake Michigan and Lake Huron, two of the Great Lakes. This water body supports a diverse aquatic ecosystem, including lake trout, whitefish, and other native species. The Straits are also a key migratory route for fish and birds. Protecting water quality here is essential for the health of the entire Great Lakes system.