It was the largest oil spill that contaminated fresh water in Washington since June 1999, when 277,000 gallons of gasoline spilled from the Olympic pipeline in Whatcom County.

Of the approximately 18,000 gallons spilled near the ski area, more than 10,000 gallons was recovered, state Department of Ecology officials said. The rest of the fuel is believed to have flowed into Silver Creek, a salmon-bearing stream and White River tributary.

The state Department of Ecology, the U.S. Environmental Protection Agency, the U.S. Forest Service, Puget Sound Energy and various contractors devoted more than a month to emergency cleanup. The fine was announced Tuesday.

Puget Sound Energy spent more than $16 million for cleanup, reimbursed $90,000 in state response costs, and cooperated with state and federal investigators, said Dale Jensen, state spills program manager.

“PSE regrets that the spill occurred,” said Steve Secrist, Puget Sound Energy director of environmental policy.

“We have implemented extensive remediation, revegetation and protective measures at Crystal Mountain that significantly reduce the likelihood that a similar spill will occur and ensure that backup protections are in place for such an unlikely event,” he said.

As for the fine, Secrist said he does not foresee an appeal. But he added that Puget Sound Energy officials had not yet received an official notice and are likely to ask some questions before the penalty is resolved. “I fully expect PSE is going to pay a fine,” he said.

The spill occurred after an electrical switch burned out, state and federal officials said. At some point, the switch got stuck in the “on” position and continuously pumped diesel into a small tank that feeds the generator engine. The tank overflowed before the spill was discovered and the pump station shut down.

Susan Gordon: 253-597-8756