Court ruling favors new runway

OLYMPIA — The Washington Supreme Court has largely overturned an environmental ruling that had stalled construction of a third runway at Seattle-Tacoma International Airport.

In a unanimous opinion, the court mostly rejected a complex set of challenges to a water-quality permit the port needs to build the airstrip — ending the latest fight in a long campaign to prevent its being built at all.

The Department of Ecology issued the permit in 2001, but in 2002, the state Pollution Control Hearings Board imposed further conditions on the project. Most importantly, it invalidated a particular test, saying it wasn’t precise enough to ensure that toxic chemicals in fill dirt wouldn’t pollute the water.

Ecology and the Port of Seattle challenged some of the conditions, arguing that the board overstepped its authority, and the high court largely agreed.

“Because Ecology is the agency designated by the Legislature to regulate the state’s water resources … this court has held that it is Ecology’s interpretation of relevant statutes and regulations that is entitled to great weight,” Justice Bobbe Bridge wrote.

The decision is a victory for the port and a loss for airport-area communities, environmentalists and other opponents of the runway.

“The state cloud over the third runway and particularly the conditions under which the runway can be built have now been cleared up,” said Linda Strout, chief counsel for the Port of Seattle.