In 1841
Charles Wilkes of the U.S. Exploring Expedition uses the name "Willamette". He notes the islands at the mouth of the Willamette River.
"... The scenery before reaching the lower mouth of the Willamette, is diversified with high and low land, which, together with three lofty snowy peaks, afford many fine views. The country begins to open here, and is much better adapted to agriculture than that lower down. ..." [Wilkes, May 1841]
"... theupper mouth of the Willamette, which flows into the Columbia, between Billy Bruce and Johnson's Islands. From this point, the river takes a bend to the southeast ..." [Wilkes, Chapter XVII]
The meaning of the word "Willamette" is not known, but according to
Oregon Geographic Names (McArthur and McArthur, 2003) one historian stated the name means "spill water" and was applied to the river above
Willamette Falls.