The study, led by researchers at Lake Superior State University, analyzed oil spill reports from 2015 to 2024.
Most of the spills happened in U.S. waters and were tied to shipping. The majority of Canadian spills were related to industrial facilities.
But the findings show only 35% of incidents on American waters reported how much oil was spilled.
Data on Canadian spill amounts did not exists until 2023, according to the study.
The data illustrates a gap in timely reporting and lack of knowledge about how much oil is seeping into the Great Lakes.
Researchers say more detailed data will shed new light on ecological damage caused by the spills.
