U.S. Route 20 follows the valley of the river from near its headwaters in the mountains to the Willamette Valley northwest of Lebanon.[4]
Tributaries
Named tributaries from source to mouth are Sevenmile and Latiwi creeks at the headwaters, then Three, Sheep, Elk, Soda Fork, Stewart, and Keith creeks. Then come Boulder, Little Boulder, Trout, Falls, Moose, Canyon, and Wolfe creeks. Further downstream are Dobbin, Soda, Cabin, Bucksnort, Mouse, and Deer creeks.[4]
Below those are Shot Pouch Creek and the Middle Santiam River. Then come Ralston, Gadney, Wiley, Ames, Roaring, McDowell, Hamilton, and Onehorse creeks followed by Spring Branch. Entering the lower reaches of the river are Crabtree, Thomas, and Mill creeks, and the North Santiam River.[4]
^McArthur, Lewis A.; McArthur, Lewis L. (2003). Oregon Geographic Names (Seventh ed.). Portland, Oregon: Oregon Historical Society Press. p. 848. ISBN0-87595-277-1.
^ abcdef"United States Topographic Map". United States Geological Survey. Retrieved December 1, 2015 – via ACME Mapper. The map quadrants include river mile (RM) markers for the river's entire length.
^"Watershed Issues". South Santiam Watershed Council. Retrieved July 25, 2009.