A makeshift army of volunteers, trail experts and public-works crews is busy cleaning up the worst wind damage to East King County trails in at least a decade.

Last month's windstorms brought a fierce eastern wind that swept through the Cascades and blew down trees along the Interstate 90 corridor, particularly on Tiger Mountain.

Cougar, Squak and Rattlesnake mountains also were hit, and some trails in the Issaquah Alps, and some near Renton and Maple Valley, remain closed.

The cleanup was complicated by last week's snowstorm, which brought down already-weakened trees and branches across the region.

"A lot of these areas were pretty much cleared up and then it's this double whammy," said Logan Harris, spokesman for the King County Department of Natural Resources and Parks.

The wind damage is stunning, even to experienced hikers. Large tree trunks are scattered in all directions across well-used trails, mixed with branches of all sizes.

The Washington Trails Association (WTA) said it has removed at least 400 fallen trees from Tiger Mountain and isn't close to being finished.

"There's places where the trail is like walking through a Weyerhaeuser lumber warehouse," said Scott Semans, a crew leader with the Issaquah Alps Trails Club.

"It's really a strange feeling."

On the Spring Lake/Lake Desire Trail southeast of Renton, entire hillsides were affected.

"It looks like a bomb went off," said Terry Brady, a county parks supervisor. "Large cottonwoods came down ... (and) left a crater you could park a car in."

Hundreds of people have joined work parties since early December to clear and repair the trails.

Before the holidays, the WTA gathered volunteers five times a week and joined with other groups to clear, by Christmas, many of the most popular trails, such as West Tiger 3 and Poo Poo Point on Tiger Mountain.

The more remote trails will take longer to finish, and crews probably will work until summer to fix the rest of the damage.

The Issaquah Alps Trails Club is meeting every Saturday, and the WTA is holding two or three work parties a week.

Repairing so many trails takes time, though it's usually not complex work. Some of the hardest work comes after a fallen tree's roots come out of the ground near a trail, experts said. The roots must be trimmed and the hole must be filled, and sometimes, the trail is diverted.

Large trees and exposed roots also damaged wooden boardwalks and a bridge, requiring time-consuming repairs.

Most of the work, though, involves chain-sawing large trunks, cutting smaller branches with handsaws and clearing the debris from the trail.

Organized crews are doing most of the clearing, but lone hikers have pitched in.

County officials and trail groups said they'd rather people join a work party, and said no one should use a chain saw unless certified as part of a formal group.

"You see some horror stories out there," said Greg Ball, WTA operations director. "You see people out there chain-sawing by themselves."

Whenever the work is finished, hikers probably will see the impact of the storms for much longer.

"(The trails) are going to have a different character," Semans said. "You're going to be seeing cut ends for decades."

Ashley Bach: 206-464-2567 or abach@seattletimes.com