Multnomah Channel is a distributary of the Willamette River that splits from the main stem a few miles upstream of the Willamette's convergence with the Columbia River in Multnomah County in the U.S. state of Oregon. The channel flows northwest then north around Sauvie Island for about 21.5 miles (34.6 km) to meet the Columbia River near the city of St. Helens, in Columbia County. U.S. Route 30 and tracks of the Burlington Northern Railroad run roughly parallel to the channel, and to its left, between its source and the Multnomah–Columbia county border at about the channel's river mile (RM) 12.5 or river kilometer (RK) 20.1.[1][2]
In its first 0.5 miles (0.80 km), the channel receives Miller Creek from the left, then passes under Sauvie Island Bridge, which carries Northwest Sauvie Island Road. Below the bridge, Ennis Creek enters from the left, then McCarthy Creek from the left at RM 18. Further along, Johns Creek enters from the left, and then Joy Creek enters from the left where the channel leaves Multnomah County and enters Columbia County. About 8 miles (13 km) from the mouth, the channel flows around Coon Island. Shortly thereafter, Crane Slough, which drains Crane's Lake, and the Gilbert River, which drains Sturgeon Lake, enter from the right. Then the channel receives Jackson Creek from the left and Cunningham Slough from the right before flowing around Louse Island and merging with Scappoose Bay, which is on the left. St. Helens is on the left as the channel enters the Columbia, about 86.5 miles (139.2 km) from the larger stream's mouth on the Pacific Ocean.[1][2]
The Multnomah Channel may have once been the main channel of the Willamette, especially before the Willamette was dredged and channelization, beginning in the late 19th century.
The Multnomah Channel is a secondary commercial waterway with nearly all commercial traffic being local and mostly consisting of gravel barges and work boats. It is an important recreational waterway for fishing, boating, and living. There are good salmon runs and record-sized walleye in the channel as well as sturgeon, catfish, and many smaller species. There are many moorages for both boats and floating homes. The Multnomah Channel Yacht Club and the Portland Boat Club (Oregon's oldest rowing club) are both located on the Multnomah Channel.