The Deadwood River is a tributary of the South Fork Payette River, flowing through Boise National Forest in Valley and Boise counties, Idaho in the United States. It joins the South Fork Payette River about west of Lowman. The source of the Deadwood River is below Deadwood summit on forest road 579 in the Salmon River Mountains. The Deadwood Dam was completed in 1931 and impounded the river to form Deadwood Reservoir.