A recent study reveals that thousands of small oil spills have occurred in the Great Lakes region over the past decade, yet their environmental impact remains largely unexamined. Researchers from Lake Superior State University identified more than 6,400 documented spills between 2015 and 2024 across the Great Lakes and connecting waterways, with most incidents involving less than 1,000 gallons of oil. Lake Michigan reported the highest number of spills, averaging about 150 annually.
Lead author and ecologist Cecilia Heuvel noted that while large oceanic spills often receive extensive media coverage, smaller spills in freshwater systems are less likely to be detected or studied. She emphasized the potential for these minor spills to create a persistent, cumulative effect on aquatic ecosystems, an impact that remains poorly understood due to limited data.
The study drew on publicly available records from the U.S. Coast Guard’s National Response Center and Canadian authorities in Ontario. However, information gaps were evident: approximately one-third of U.S. incidents included spill volume data, and Canadian records provided no volume details prior to 2023. The most common cause of spills in the U.S. was related to shipping activities, whereas facility-related incidents predominated in Canada.
The risk posed by pipelines to freshwater environments has been highlighted by notable incidents. In 2010, a rupture in the Line 6B pipeline released over 845,000 gallons of hydrocarbons into the Kalamazoo River, a tributary of Lake Michigan. Cleanup efforts cost more than $767 million, and hundreds of residents reported health symptoms linked to crude oil exposure. Despite the spill, Enbridge, a Canada-based energy company, continues to operate the pipeline—now rebranded as Line 78—transporting more than 500,000 barrels of crude oil daily.
More recently, in August 2024, a flatbed truck collision with Line 5 in Wisconsin caused a release of roughly 31,000 barrels of natural gas liquids, primarily propane and butane, into the atmosphere over four days. Line 5 crosses beneath the Straits of Mackinac, a critical waterway, and has drawn scrutiny from environmental groups who argue it poses a significant threat. Enbridge’s proposed plan to replace part of Line 5 with a tunnel was rejected by the Michigan Supreme Court, which called for additional environmental review.
Environmental advocates remain critical of ongoing pipeline operations. Liz Kirkwood, strategic partnership officer at Flow Water Advocates, described Line 5 as a "ticking time bomb" and dismissed the tunnel project and reroute proposals as inadequate solutions. She stressed the age of the pipeline and advocated for its shutdown to protect the Great Lakes.
Separately, environmental organizations have raised concerns about a recent surge in U.S. pipeline construction, attributing it to deregulation measures implemented during the Trump administration. The Environmental Integrity Project reported that at least 25 percent of 193 proposed or under-construction natural gas pipelines have sought expedited review processes under the administration’s 2025 national energy emergency declaration. Critics argue the emergency was unwarranted and has been used to fast-track projects that pose environmental risks.
Jen Duggan, executive director of the Environmental Integrity Project, described the emergency declaration as a “sham” given the country’s reliable electric grid and rising exports of oil and gas. She criticized the approach for increasing public hazards associated with pipeline incidents.
Additionally, advocacy groups point to weakened safety regulations, reduced enforcement actions, shortened public comment periods on pipeline projects, and policies limiting environmental protections. James Hiatt, founder of For a Better Bayou, criticized these abbreviated comment windows, asserting they hinder public participation in environmental decision-making.
Researchers continue to call for more comprehensive study of the cumulative effects of small freshwater oil spills and for increased regulatory oversight to safeguard the Great Lakes’ ecological health.