The South Yamhill River is a tributary of the Yamhill River, approximately 50 mi (80 km) long, in northwest Oregon in the United States. It drains an area of the Coastal Range, as well as part of the Willamette Valley west of the Willamette River.

It rises in the Siuslaw National Forest in the Coastal Range along the county line between Tillamook and Yamhill counties, near the Grande Ronde Indian Reservation . It flows SSE, then generally ENE, through the Van Duzer State Forest , past Grande Ronde and Sheridan, then northwest, joining the North Yamhill River from the south approximately 2 mi (3.2 km) east of McMinnville to form the Yamhill.

In its upper reaches in the mountains it flows through timber-producing forests, broadening into an agricultural valley and emerging into the larger Willamette Valley near Sheridan. The valley of the river is especially fertile, with many orchards and berry farms.

The river valley is essentially a break in the line of higher mountains in the Coastal Range, located in a region of gentle hills between the coast and the Willamette Valley. The valley provides the route of Oregon State Highway 18 , one of the most popular routes to the Oregon Coast from Portland and the population centers of the northern Willamette Valley.

See also

• List of Oregon rivers