[3] It rises in the Rocky Mountains at the continental divide in the Beaverhead-Deerlodge National Forest in western Jefferson County.

It flows east and southeast through the mountains past Boulder, then south to join the Jefferson near Cardwell.

[5] Game fish in the river include brook, brown, and rainbow trout, and mountain whitefish.

[6] The lowermost 12 miles (19 km) of the river is affected by irrigation withdrawals, and the reach below the community of Basin is affected by seepage from old mines and tailings.

This article related to a river in Montana is a stub.