A portion of the Historic Columbia River Highway State Trail west of Bonneville Dam is closed to accommodate freeway bridge work on Interstate 84 near Tanner Creek. The trail closure affects the state trail west of the Tooth Rock Trailhead. Forest Service Trail 400, in the same area, will remain open. The Historic Columbia River Highway State Trail east of Tooth Rock will also remain open. Where motorists on old U.S. Highway 30 once crept around curves high along the cliffs of the Columbia River Gorge, hikers, bicyclists and users of other muscle-driven forms of transportation leisurely enjoy the view from the Historic Columbia River Highway State Trail. The trail, two disconnected paved ribbons along abandoned stretches of the historic highway, give you more than 10 miles of sightseeing thrills. Between Hood River and Mosier, the five mile Twin Tunnels segment passes through two climate zones. Starting at the east Mark O. Hatfield Trailhead near Mosier, the trail leads through semi-arid terrain dotted with ponderosa pine for about a mile until you reach the Twin Tunnels. Spectacular geologic formations tell the story of the gorge's creation. After passing through the tunnels, you'll emerge into a forest of fir trees and other common western Oregon plants. Viewpoints along the 3.5 mile segment from the tunnels to the west Mark O. Hatfield Trailhead overlook the river. Both trailheads for the Twin Tunnels segment require a day use pass $3 ($5 on 01/01/2010) daily day-use fee or buy a 12-month permit for $25 ($30 on 01/01/2010) or a 24-month permit for $40 ($50 on 01/01/2010). A yellow self-service machine dispenses daily passes at each trailhead. There's a visitor center at the west trailhead with brochures and other information. The other open, paved section of the trail parallels Interstate 84 between Cascade Locks and Bonneville Dam (the trail actually extends from Moffett Creek to Cascade Locks). Lush and green, this segment gets twice as much rainfall as the Twin Tunnels area. Ferns, moss-covered rocks and delicate, shaded wildflowers flank the 2.5 mile section from Cascade Locks to the Eagle Creek Fish Hatchery. The trail then continues for another mile west to the Tooth Rock Trailhead, with views of Bonneville Dam along the way. Several U.S. Forest Service trails intersect this segment of the trail. All segments of the trail are rated moderate to difficult for people with disabilities.