The two largest tributaries of the Deschutes are the Metolius River and the Crooked River. The Metolius begins at Metolius Springs and runs northeast, flowing into the Deschutes from the west just south of Round Butte Dam. The Crooked River flows west from its sources in the Ochoco Mountains and the Oregon high desert. It flows into the Deschutes from the east at Cove Palisades State Park. Both rivers merge into the Deschutes River, becoming part of Lake Billy Chinook, the reservoir created by the Round Butte Dam.