Graham Sustainability Institute

U-M Water Center Scientist Develops Straits of Mackinac Contaminant Release Scenarios

Thursday, July 10, 2014

The Straits of Mackinac is the roughly 10 km long section of waterway connecting Lakes Michigan and Huron into a single hydraulic system. It is spanned at its narrowest point by the Mackinac Bridge which connects Michigan’s upper and lower peninsulas. Tens of thousands of trucks pass over the bridge each year and hundreds of cargo vessels pass under it. Just west of the Mackinac Bridge, the Straits are also spanned by two submerged oil pipelines that carry up to 23 million gallons of crude oil and natural gas fluids each day.

Currents in the Straits can be as strong as currents in the Detroit River and tend to reverse direction between eastward and westward flowing every few days. Peak volumetric transport through the Straits can reach 80,000 cubic meters per second (more than 10 times the flow of the Niagara River). Flow through the Straits can play an important role in water quality, contaminant transport, navigation, and ecological processes.

To better understand and communicate these unique flow conditions, the National Wildlife Federation commissioned U-M Water Center research scientist David Schwab to produce computer simulations and animations of hypothetical releases in the Straits. The results can be viewed in the animation and full report below. It is the hope that these simulations and animations will be useful in understanding and preparing for potential impacts of an accidental contaminant release in the Straits.