Lewis River (Washington)
Lower Falls of the Lewis River, about 15 km above Swift Reservoir. (46 ° 9 ' 25 "N, 121 ° 52' 38 " W46.156946 - 121.877089 )
The Lewis River is a 153 km long tributary of the Columbia River in the southwestern part of the U.S. state of Washington. It drains part of the Cascade Range north of the Columbia River.
In contrast to the nearby Lewis County and Fort Lewis this river was not named after the explorer Meriwether Lewis, but after a settler named A. Lee Lewis, who settled one of the first at the river mouth.
Run
The Lewis River - sometimes called North Fork Lewis River - rises in the northeast of the Skamania County east of Mount Adams in the Cascade Range, about 120 km north-east of Portland. It flows roughly southwest through the Gifford Pinchot National Forest in the middle of the Skamania County on the south side of Mount St. Helens over. From here it forms the border between the Cowlitz County in the north and the Clark County in the south. In the last 15 km of its course it turns sharply to the south and then bends westward to empty into the Columbia River across from St. Helens, about 24 km north of Vancouver, Washington. Settlements lie on the lower reaches: Cougar, Ariel and Woodland - all on the right, the north bank and thus in Cowlitz County. In the area of the mouth of the Lewis River is located on the Columbia River, the Ridgefield National Wildlife Refuge, a nature reserve on the type of a National Wildlife Refuge under the administration of the United States Fish and Wildlife Service.
Just before the confluence with the Columbia River, the river still takes the water from the East Fork Lewis River. The headwaters of the East Forks is located on the west side of Lookout Mountain in Skamania County. At its westward course are in Clark County, the settlements Heisson and La Center and the Paradise Point State Park. Also the name of South Fork Lewis River is common for the East Fork.
Reservoirs along its course
For purposes of generating electricity by water power of the river is dammed several times and forms a chain of reservoirs Swift Reservoir, Yale Lake and Lake Merwin.
Hydrographic
In the catchment area of the Lewis Rivers of the United States Geological Survey operates a number of levels.
The annual average discharge of the Lewis River (1924-2006) in Ariel, about 30 km upstream of the confluence with the Columbia River, is 135 m³ / s The catchment area has up to this point, an area of 1893 km ². The highest observed river discharge on December 22, 1933 were approximately 3600 m³ / s, the lowest flow rate was zero and was measured on several days between 30 June and 9 July 1931 construction work on the Merwin Dam prevented the drain.
About 32 km upstream of the confluence with the main branch is located at Heisson the level of the East Fork Lewis River, whose catchment area up to this point covers 324 km ². The recordings take place there continuously since September 1929. Annual average discharge is here 21 m³ / s The highest runoff was s observed on 8 February 1996 with 800 m³ /, the lowest measured discharge amount of 0.8 m³ / s was measured on 3 November 1935, and on 27 and 28 September 1967.