Calgary-based energy giant Enbridge is being ordered by U.S. authorities to do more to clean up a big oil spill that happened in southwest Michigan more than two-and-a-half years ago.

About three million litres of oil leaked from an Enbridge pipeline that ruptured in July 2010 near Kalamazoo.

The U.S. Environmental Protection Agency (EPA) says it's still finding oil in parts of the Kalamazoo River and is ordering Calgary-based Enbridge to do more dredging to remove submerged oil.

The agency is also ordering Enbridge to maintain sediment traps throughout the river to capture oil outside the area being dredged.

The EPA is giving Enbridge 15 days to come up with a plan and says the dredging should start this spring.