The state Pollution Control Hearings Board has opted to stay the effect of a water quality permit until March, when the panel plans to rule on an appeal of the permit issued earlier this year by the state Department of Ecology. The permit is necessary if the airport is to receive another, and final, permit from the U.S. Army Corps of Engineers.

The group, which filed the appeal, the Airport Communities Coalition, claims the board's ruling could serve as a "fatal blow" to the already controversial project. The permit was one of the last remaining hurdles toward the construction of a third runway at Sea-Tac. The Airport Communities Coalition, which has battled airport expansion for years, had accused the DOE of bowing to political pressure.

The Port of Seattle wants to build an 8,500-foot runway west of Sea-Tac's existing runways by building up the airport's property with more than 17 million cubic yards of dirt. Wetlands and three streams with fish are in the vicinity.