An estimated 2,500 gallons of diesel spilled on the ground within a few dozen feet of a Southwest Alaska river after a tractor-trailer truck accident, state officials said Monday.

The truck, lugging a 9,500-gallon fuel tank for village use, was headed down the Pile Bay Road toward Iliamna on Friday. As the tank was being unhitched from the truck, it rolled down an incline and ruptured, regulators said.

Workers plugged the hole in the tank and piled up mounds of dirt that kept the diesel from running directly into the Iliamna River, regulators said.

Workers stopped the leading edge of the spill 25 feet from the river, state regulators said Monday, citing a report from Alaska State Troopers.

The Alaska Department of Environmental Conservation cited Iliamna Development Corp., a subsidiary of the village Native corporation for Iliamna, as the responsible party for the spill. Removal of the contaminated dirt will begin shortly, a department official said.

The Iliamna Development Corp. did not immediately return calls for comment on Monday.

"It's a good-sized spill," said John Brown, a DEC environmental specialist.

"We are very concerned about it being so close to the river."

Brown estimated that the diesel spread over an area measuring 15 feet by 200 feet. "It just goes right into the soil, and if it isn't cleaned up, it goes to the water table and then to the river," he said.

The contaminated dirt must be disposed of as hazardous waste, according to DEC.

One thing that remained unclear Monday was how Iliamna Development planned to get the fuel to the village from Pile Bay Road. The village is not directly accessible from the road because it is on the other side of Iliamna Lake.

"I don't know how they were going to get it there," Brown said.