Between Gibbon and Cayuse, three creeks—Squaw, Buckaroo, and Coonskin—enter the river from the left. Downstream of Cayuse, Moonshine, Cottonwood, and Mission creeks also enter from the left.
The rivers receive tributaries from Gibbon and Cayuse on the left, including Squaw, Buckaroo, and Coonskin creeks. Furthermore, Moonshine, Cottonwood, and Mission creeks also enter the river from the left in a downstream location.