An oil spill in Alaska's North Slope could end up being one of the region's largest, officials said Wednesday as the cleanup continued.

Crews have recovered 58,590 gallons — or 1,395 barrels — of crude and snow since the pipeline spill was discovered Thursday in the Prudhoe Bay field, about 650 miles north of Anchorage. Most of the recovered material will probably turn out to be crude once the water is separated out, officials said.

That means the spill could be the largest ever in the North Slope, surpassing a 38,850-gallon spill in 1989. By comparison, the Exxon Valdez spilled 11 million gallons when it ran aground in Prince William Sound in 1989.

Lynda Giguere of the Alaska Department of Conservation said officials should have an estimate Thursday of how much crude spilled onto a two-acre area from the line, which leads to the trans-Alaska pipeline.

Temperatures are well below zero and are expected to approach 60 below in coming days, complicating the cleanup, officials said.

The North Slope is the region between the Brooks Range and the Arctic Ocean and contains most of Alaska's petroleum reserves.