In its final miles, the Entiat River turns east to join the Columbia River at Columbia river mile 483.7, just south of the small city of Entiat. At this point the Columbia River is a reservoir created by Rocky Reach Dam. The reservoir's name is Lake Entiat. Fern Lake is located at the headwaters of the North Fork Entiat. Entiat Glacier, located in a cirque on the eastern side of Mount Maude and Seven Fingered Jack, is the headwaters of the Entiat River.