STS068-174-152 Columbia Plateau and Snake River, Washington, U.S.A. October 1994 The southeastern portion of the Columbia Plateau in Washington is visible in this west-southwest-looking, low-oblique photograph. The Snake River, the Columbia River's chief tributary, is visible as it travels westward to enter the Columbia River near Pasco, Washington. The Spokane River empties also into the Columbia River. Lava flows cover much of the Blue Mountains--the uplifted, eroded part of the Columbia Plateau. Scattered agricultural field patterns appear throughout the photograph.