The name, spelled "Entiat", was selected for the river in 1958 by the Chelan County Public Utility District.

Over 90% of the drainage basin of the Entiat River and its tributaries is publicly owned property, mostly the Wenatchee National Forest.

A large number of place names in the Entiat River basin were given by Albert H. Sylvester.

The Entiat River's headwaters lie in the Glacier Peak Wilderness of the Wenatchee National Forest.

Its main source comes from the slopes of Mount Maude and Seven Fingered Jack, and Entiat Glacier.