Source: pipe-up.net

An aging oil pipeline burst on July 25, 2010 and spilled more than one million gallons of heavy Canadian tar sands bitumen oil into the Kalamazoo River. It was the largest inland oil pipeline spill in U.S. history. The Kalamazoo accident was the first major pipeline spill involving diluted bitumen, or dilbit, the same type of oil that will be carried by the Keystone XL pipeline if the Obama administration approves the project.

"You can look at the river and say it looks good but there are so many things that fly under the radar–those are the things that we will be monitoring for years," said Michelle DeLong, who is leading the Michigan Department of Environmental Quality (MDEQ).