 Passing through the cities of Gresham, Portland, and Milwaukie, the creek flows generally west from the foothills of the Cascade Range through sediments deposited by glacial floods on a substrate of basalt.Though polluted, it is free-flowing along its main stem and provides habitat for salmon and other migrating fish.Prior to European settlement, the watershed was heavily forested and was used by Native Americans of the Chinook band for fishing and hunting.