Canadian Pacific Railway Ltd's oil spill in Minnesota is now estimated at less than 15,000 gallons, down slightly from earlier estimates of between 20,000 and 30,000 gallons, Minnesota officials said.

Freezing temperatures at the site have made it difficult to take up the spilled oil, said Dan Olson, spokesman for the Minnesota Pollution Control Agency, and the cleanup is expected to take another day or two.

So far, 1,000 gallons of spilled oil have been recovered following the derailment, Olson said.