About 21.8 million pounds — or nearly 10,000 metric tons — of plastic flow into the Great Lakes each year from the United States and Canada, according to a new study from the Rochester Institute of Technology.
The results are alarming: 5,000 metric tons of plastic winds up in Lake Michigan each year. 2,500 metric tons enter Lake Erie, 1,400 metric tons enter Lake Ontario, 600 metric tons enter Lake Huron, and 32 metric tons enter Lake Superior.
In Lake Michigan, that's approximately the equivalent of 100 Olympic-sized pools full of plastic bottles dumped into the lake every year, according to the report. For Lake Ontario, that's 28 Olympic-sized pools full of plastic bottles.
The authors — Matthew Hoffman, an assistant professor at RIT's School of Mathematical Sciences, and Eric Hittinger, an assistant professor of public policy at RIT — calculated the amount of plastic flowing into the lakes using population totals along the shores of each of the five lakes and existing estimates for the amount of plastic waste individuals produce. The formula is based on a previous study that estimated 8 million tons of plastic enter the world's oceans annually.
The researchers used computer simulations to track how currents moved plastic debris. Because of how lake currents work, debris travels across lakes to the opposite shores. That means major cities like Chicago, Toronto, Cleveland, and Detroit pollute more plastics than accumulate on their shorelines. Here's a video simulation of Lake Erie in 2009: