An environmental group says Enbridge Inc., thecompany whose ruptured pipeline dumped 800,000 gallons of oil into the Kalamazoo River, has a long history of spills.

Wednesday is the second anniversary of the spill near Marshall, Mich.

The National Wildlife Federation says Enbridge had 804 pipeline spills in 1999-2010, releasing a combined 6.8 million gallons of oil. Federation vice president Jeremy Symons says mistakes and bad luck can’t explain such a high number.

Enbridge spokesman Graham White said most of Enbridge’s spills are small and contained at pump stations and terminals. He said they have little environmental impact and are cleaned quickly.

The federation proposes regulating pipelines used to transport heavy tar sands oil. The National Academy of Sciences is investigating whether tar sands oil is tougher on pipes than conventional oil.