The main Coos River flows only about 5 miles into Coos Bay. Although there are many tributaries that flow into the river, it is comprised mostly of the Millicoma River and South Coos River flows. It travels mainly in a westward flow into the eastern end of Coos Bay near the city of Coos Bay and is the largest estuary that lies completely within the borders of Oregon. Coos Bay is approximately 15 miles long and runs through the cities of Coos Bay, North Bend, Barview and Charleston where it finally spills into the Pacific Ocean.
The South Fork Coos River is a tributary of the Coos that is approximately 32 miles long. It is a confluence of the Williams River and Tioga Creek and begins in eastern Coos County near the Douglas County line. It runs in a northwest direction through the Southern Coast Range. East of the city of Coos Bay it joins the Millicoma River and forms the Coos River.
The Coos River is fished for Chinook and Coho Salmon, Steelhead, cutthroat trout, and shad. It has been rated as one of Oregon's top salmon and steelhead fisheries. The fall Chinook run generally begins in July or August and lasts through late October. Coho are generally fished in the bay and are open for fishing in October and November. Winter steelhead fishing season runs from December to March with the most fish being caught in January and February.
Within the bay, the fishing does not include just the salmon and steelhead, but sturgeon and bottom fish as well. Sturgeon can be fished usually starting in March or April and running as late as August. Bottom fishing is open year round.