Multnomah Channel - Course

Course

Constrained by dikes, the channel is about one-third as wide as the lower Willamette main stem. 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.

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 (RK 29). 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.