Original sentence: From its headwaters in the Bitterroot Mountains of eastern Idaho, it flows southwest, north, then again southwest, and is dammed by the Dworshak Dam just above its mouth at the Clearwater in central Idaho
Edited sentence: From its headwaters in the Bitterroot Mountains of eastern Idaho, it flows.southwest, north, then again southwest, and is dammed by the Dworshak Dam just above its mouth at the Clearwater in central Idaho