Modernizing Mackinac Island: Major Infrastructure Investment Supports Community’s Future

Nearly 500 people live on Mackinac Island year-round, but every summer, the population surges to more than 20,000. This increased population puts a major strain on the island’s more than 50-year-old wastewater treatment plant.

Today, thanks to a $78.7 million investment supported by the State of Michigan, that same facility is being transformed to ensure clean drinking water, better protect the Great Lakes, support tourism and serve the island’s needs for generations to come.

During the 2025 Mackinac Policy Conference, Michigan Department of Environment, Great Lakes, and Energy (EGLE) Director Phil Roos joined city leaders, legislators, and stakeholders for a tour of the plant, calling it a model for strategic, community-centered water infrastructure projects.

“This project is a shining example of how investing in our water infrastructure protects public health, boosts local economies, and safeguards the natural resources that define our state,” said Roos. “From world-class tourism destinations like Mackinac Island to smaller towns across Michigan, we are committed to helping communities build the modern systems they need to thrive.”