The Washington State Department of Natural Resources sent firefighters to a fire on Cottonwood Island, which lies on the Columbia River between Longview and Kalama.
The brush fire on the 700-acre island, which is land protected by DNR, was reported around 4 p.m.
Clark County Fire & Rescue used its fire boat to ferry DNR firefighters to the island from the Kalama marina, said Battalion Chief Tim Dawdy. A Clark County Sheriff's Office marine patrol boat also went to the island to help out.
DNR ferried five engines over to the island, said agency spokesman Bob Redling. He wasn't sure how big the fire was, though initial reports estimated it spanned half an acre.
Meanwhile, message boards along Interstate 5 alerted drivers about smoke from the fire drifting onto the roadway, Redling said. Cowlitz County authorities ask that people don't call 911 about the fire or the smoke on the freeway. There is no threat to people or buildings as no one lives on Cottonwood.
Crews planed to work until dark today and will return to the island tomorrow as needed. It's unclear so far what started the fire.