The Sun River Dam begins in the Bob Marshall Wilderness Area and flows on the east side of the Rocky Mountain Front. From its origin, the river flows for a little over five miles before the river flows through two dams, the Gibson Dam and the Sun River Dam located three miles further downstream. These dams regulate the flows of the Sun, frequently leading to low water during the summer as irrigation draws off much of the Suns flows.

Below the Sun River Dam and lasting for the next twenty-five miles, the Sun River turns into a very isolated and wild river. The river first flows through the Sun River Canyon, a steeply sloped canyon providing wild and remote scenery on the edge of the Rocky Mountain Front.