_Obsidian Creek_--E : 6--1879--Norris--Characteristic.
_Opal Creek_--E : 12--1885--U. S. G. S.--Characteristic.
_Otter Creek_--H : 8--1885--U. S. G. S.--Characteristic.
_Outlet Creek_--P : 9--1895--U. S. G. S.--Characteristic.
_Owl Creek_--T : 5--1885--U. S. G. S.--Characteristic.
_Pacific Creek_--W : 11--1873--Jones--Flows from Two-Ocean Pass down the Pacific slope.
_Panther Creek_--D : 5--1878--U. S. G. S.--Characteristic.
_Pebble Creek_--D : 13--1885--U. S. G. S.--Characteristic.
_Pelican Creek_--K : 10--Probably named by the Washburn Party in 1870. Hayden and Barlow, in 1871, use the name as though it were already a fixture. Mr. Hedges says of this stream:
"About the mouth of the little stream that we had just crossed were numerous shallows and bars, which were covered by the acre with ducks, geese, huge white-breasted cranes, and long-beaked pelicans, while the solitary albatross, or sea-gull, circled above our heads with a saucy look that drew many a random shot, and cost one, at least, its life."
_Phlox Creek_--Q : 13--1885--U. S. G. S.--Characteristic.
_Plateau Creek_--C : 12--1885--U. S. G. S.--Characteristic.
_Polecat Creek_--S : 6--1885--U. S. G. S.--Characteristic.
_Quartz Creek_--E : 10--1885--U. S. G. S.--Characteristic.
_Rabbit Creek_--K : 4--1885--U. S. G. S.--Characteristic.
_Raven Creek_--J: 12--1885--U. S. G. S.--Characteristic.
_Red Creek_--Q: 8--1885--U. S. G. S.--Characteristic.
_Rescue Creek_--C: 7--1878--U. S. G. S.--Where Everts was not found. (See "Mt. Everts.")
_Rocky Creek_--O: 12--1885--U. S. G. S.--Characteristic.
_Rose Creek_--D: 12--1885--U. S. G. S.--Characteristic.
_Sedge Creek_--K: 11--1885--U. S. G. S.--Characteristic.
_Senecio Creek_--S: 13--1885--U. S. G. S.--Characteristic.
_Sentinel Creek_--J: 4--1872--U. S. G. S.--"The two central ones [geyser mounds] are the highest, and appear so much as if they were guarding the Upper Valley, that this stream was called Sentinel Branch." Bradley.
_Shallow Creek_--F: 11--1895--U. S. G. S.--Characteristic.
_Sickle Creek_--Q: 10--1885--U. S. G. S.--Characteristic.
_Slough Creek_--D: 10--1867--See "Crevice Creek."
_Snake River_ (6,808)--W: 8--1805--Lewis and Clark--From the Snake or Shoshone Indians, who dwelt in its valley.