Nespelem River before the river empties into the Columbia River. This reach of the Columbia River is several miles below Grand Coulee Dam and many miles above Chief Joseph Dam. The impounded Columbia River behind Chief Joseph Dam, into which the Nespelem River flows, is called Rufus Woods Lake. Nespelem River The Nespelem River is a northern tributary of the Columbia River, in the U.S. state of Washington. It is completely contained within Okanogan County and the Colville Indian Reservation. The name "Nespelem" is said to come from the Indian word "nesilim", meaning "flat land". The Nespelem River originates in eastern Okanogan
Grand Coulee wide as Niagara Falls and three times as high. Steamboat Rock high and a in area, now stands as an isolated rise, but for a time it created two cataract. When the falls passed north of Steamboat Rock, it found a granite base beneath the basal flows. Granite lacks the close vertical joints of basalt, was resisted the erosion from the cataract's plunge. It remains as hills on the broad floor of the Coulee. Some gravel-bar deposits are visible along the Route 155. They provide evidence of eddies in the lee of rock shoulders. Dry Falls is at the head