Did you know that the Enbridge oil spill in the summer of 2010 was the largest onshore oil spill in U.S. history? The incident caused more than 20,000 barrels of heavy Canadian crude to gush into the Kalamazoo River system near Marshall, Michigan. Enbridge Energy Partners LLP recently estimated the cleanup costs at $820 million and said that the final sum may exceed its insurance coverage and impact its financial results. The oil, which originated in western Canada, spilled from a pipeline that carries 231,000 barrels a day from northern Indiana to Sarnia, Ontario.