Fuel vault at Anchorage medical campus believed to be source of University Lake oil spill

A fuel vault at Alaska Native Medical Center is believed to be the source of an oil spill that polluted a lake and prompted the closure of a popular off-leash dog park in Anchorage, an official with the state Department of Environmental Conservation said Friday.

The spill was first reported at University Lake on June 21 and initially estimated to be about 20 gallons in size, although it is challenging to tell exactly how much oil spilled into the water, said Kelly Rawalt, a spokeswoman for department. The municipality closed the surrounding park on June 28.

Cleanup efforts continued this week at the lake. Oil absorption strips floated on top of the water and multiple barriers surrounded the edges of the spill to prevent the oil from spreading more. Crews vacuumed the sheen from the surface of the water, and a skimmer device helped filter the oil from the lake.

The Department of Environmental Conservation worked with the municipality and the Environmental Protection Agency to track down the source of the oil, Rawalt said. They believe a fuel vault — an underground storage container — on the Alaska Native Medical Center campus was the source of the spill, she said.

The vault is connected to the municipal drainage system, Rawalt said. Authorities believe excess rainwater flooded the vault and then went into the drainage system, where a device that filters oil from the water malfunctioned, she said.

Oil is no longer spilling into the lake, according to Rawalt, and officials are making sure the fuel vault won’t release more oil in the future. They are also monitoring the device in the municipal drainage system that malfunctioned, she said.

It’s not clear how much longer it will take to clean the lake or when the park might reopen. Responders this week were working to remove oiled vegetation and using predator decoys and other hazing tactics to keep birds away from the area.

Rawalt urged people to avoid the lake while the park is closed. The U.S. Fish and Wildlife Service and Alaska Department of Fish and Game were monitoring wildlife for suspected impacts, and dogs running toward the water can cause wildlife to head toward the polluted area, she said.

“We want to make sure that it’s safe for people to return,” Rawalt said.