The Sixes River is a river, approximately 30 mi (48 km) long, in southwestern Oregon in the United States. It drains a rugged region of the Coastal Range along the Pacific coast south of Coos Bay.
13,700 acres (55.4 km2) along the North and South Forks of Elk River and the upper Middle Fork of Sixes River in under consideration for wilderness designation as the Copper Salmon Wilderness. The area contains one of the nation's largest remaining stands of low-elevation old-growth forest and one of the healthiest salmon, steelhead, and cutthroat trout runs in the continental United States along the north Fork of the Elk River, as well as stands of vulnerable Port Orford cedar and endangered marbled murrelets and northern spotted owls.1