Fireworks set off by someone in a boat on the Fourth of July may have started the wildfire that burned more than three square miles above the north shore of Lake Chelan near Manson.
Department of Natural Resources spokeswoman Janet Pearce says investigators would like to find whoever reportedly set off fireworks Thursday from a boat on the lake.
The fire has burned grass, brush and scattered trees on private and Forest Service land.
Fire managers said Monday the fire is 50 percent contained and the chance it could threaten structures is significantly reduced.
Nearly 100 firefighters have been demobilized to make them available for other fires. About 230 remain on the scene, with help from three helicopters, which have been dipping water from Lake Chelan.