| Coos River | |
| Name Etymology: | Indian name for a native tribe living near Coos Bay[1] |
| Map Size: | 300 |
| Pushpin Map: | USA Oregon |
| Pushpin Map Size: | 300 |
| Pushpin Map Caption: | Location of the mouth of the Coos River in Oregon |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | Oregon |
| Subdivision Type4: | County |
| Subdivision Name4: | Coos |
| Length: | 5miles[2] |
| Discharge1 Avg: | 1441cuft/s[3] |
| Source1: | Confluence of Millicoma River and South Fork Coos River |
| Source1 Location: | Coos County, Oregon |
| Source1 Coordinates: | 43.3775°N -124.0992°W |
| Source1 Elevation: | 13feet[4] |
| Mouth: | Coos Bay |
| Mouth Location: | Coos Bay, Coos County, Oregon |
| Mouth Coordinates: | 43.3625°N -124.1736°W[5] |
| Mouth Elevation: | 0feet |
| Basin Size: | 730sqmi |
The Coos River flows for about 5miles into Coos Bay along the Pacific coast of southwest Oregon in the United States.[2] Formed by the confluence of its major tributaries, the South Fork Coos River and the Millicoma River, it drains an important timber-producing region of the Southern Oregon Coast Range.[6] The course of the main stem and the major tributaries is generally westward from the coastal forests to the eastern end of Coos Bay near the city of Coos Bay.[7]
The river is the largest tributary of Coos Bay, which at about 10000acres is the largest estuary that lies entirely within Oregon.[6] The river enters the bay about 15miles[6] from where the bay - curving east, north, and west of the cities of Coos Bay and North Bend and passing by the communities of Barview and Charleston - meets the ocean.[7] About 30 other tributaries also enter the bay directly.[6]
Most of the Coos River watershed of 730mi2 is in Coos County, but 147mi2 are in eastern Douglas County.[6] Commercial forests cover about 85 percent of the basin.[6]
The river supports populations of chinook and coho salmon, Pacific lamprey,[8] western brook lamprey, shad, steelhead, and coastal cutthroat trout. Since public river-bank access is limited, fishing is often done by boat.[9]
Flowing west from the confluence of the South Fork Coos River and the Millicoma River, the Coos River is bordered by Oregon Route 241 (Coos River Highway) on the right and Coos River Road on the left. Downstream from its source, the river receives Noah Creek from the right 4miles from the river mouth. Curving south, the river receives Vogel Creek and then Lillian Creek, both from the left, before passing under Chandler Bridge, which carries Route 241 from the right bank to the left bank about 2miles from the mouth. The river then turns west and north as it enters the bay and splits into two distributaries separated by a marsh. The Cooston Channel, which is on the right, continues north around the west side of the marsh for about 1miles to the mouth. The left-hand channel almost immediately merges with Catching Slough, which enters from the left and continues around the east side of the marsh to meet the Marshfield Channel of the bay.[2] [7]
Estimates of the average discharge of the Coos River varies from 90cuft/s in late summer to 5500cuft/s in February. Estimated extremes vary from a low of 50cuft/s to a high of 100000cuft/s.[6]