Washtucna Coulee - Washington - Glacial Lake Missoula Flood Features on Waymarking.com

This location is along Wash. Hwy. 260 about four and a half miles west of Kahlotus on the rim of Washtucna Coulee. The location provides a view up and down the coulee. Washtucna Coulee extends for more than thirty miles from east of the community of Washtucna to the community of Connell.

Prior to the great Ice Age floods from glacial Lake Missoula, the Palouse River followed the route of the Washtucna Coulee westward from Washtucna to Connell and then south along the Esquatzel Coulee to the Pasco area where it joined the Columbia River. During the Ice Age floods the huge volumes of water entering the Palouse drainage from the north were so large that east of Washtucna waters spilled southward over a 9-mile wide divide into the Snake River drainage. Eventually these overflow waters carved the present day route for the Palouse River south to the Snake River. But during these Ice Age floods the old Palouse channel was also enlarged and modified to form the Washtucna Coulee of today.