Lewis River Drainage Professional Review and Guide
"The Lewis River starts in Shoshone Lake, flows south through Lewis Lake, then splashes over a series of falls and through a grand gorge to merge with the Snake River just inside the south boundary of Yellowstone National Park. Captain Lewis of the Lewis and Clark Expedition never saw any part of the park, much less the river and lake, that now bear his name.
Osbourne Russell made note of the lake in his 1839 journal. The 1872 Hayden survey named the lake to honor Captain Lewis, and then the name became attached to the river as well. This eTrail contains information on Shoshone Lake, DeLacy Creek, Shoshone Creek, Moose Creek, Lewis River Channel, Lewis Lake, and Lewis River."