With its headwaters in the icefields on the western slopes of
Mount Adams, the Lewis River flows westward through
Gifford Pinchot National Forest to the western boundary of Skamania County. From there to the
Columbia River, it represents the boundary between Cowlitz County and Lewis County. It is dammed along the way three times, by Swift Dam, by Yale Dam and by Merwin Dam. It passes through the small communities of Yale,
Ariel and
Cougar before crossing
Interstate 5 at
Woodland, near its confluence with the Columbia.
