The Lewis River is a tributary of the Columbia River, approximately 95 mi (153 km), in southwestern Washington in the United States It drains part of the Cascade Range north of the Columbia River.

It rises in the Cascades in northeastern Skamania County, east of Mount Adams approximately 75 mi (120 km) northeast of Portland, Oregon. It flows generally southwest through the Gifford Pinchot National Forest, across central Skamania county, passing south of Mount St. Helens. It forms the boundary between Cowlitz (N) and Clark (S) counties, passing Cougar, Ariel, and Woodland. In its lower 10 mi (16 km), it turns sharply south and enters the Columbia from the east opposite St. Helens, Oregon, approximately 15 mi (24 km) NNW of Vancouver, Washington.

It is impounded for hydroelectricity in its middle course to form Swift Reservoir, Yale Lake, and Lake Merwin, forming a chain of reservoirs.

External link

• USGS: Lewis River Basin (http://wa.water.usgs.gov/realtime/htmls/cowlitz.html)