Yellowstone oil spill moves into cleanup phase

Oil industry giant ExxonMobil is moving to the next phase of response following a spill in the Yellowstone River.

Crews involved have confirmed that the effort has moved on from an emergency response to a long-term cleanup process, including assessing the impact of the spill on the surrounding areas and focussing efforts on those most affected.

"We like the fact that we're moving into a cleanup phase," said Richard Opper of the state Department of Environmental Quality.

"That's a good thing for the state of Montana and that's what the citizens, particularly those impacted by the spill, want to see."

Teams inspecting the area have identified that around 60 per cent of the shoreline downriver from the oil spill has been contaminated.

This broke down to just over 40 per cent with light to very light oil, 17 per cent with moderate oil and just one per cent with heavy oil contamination.