15 sous and the HBC
Odd how coinage keeps making appearances in this website! We’ve previously looked at “picayunes“, “bits”, and more. “Quinze Sous” is French for “fifteen sous”, evidently a common coin denomination since the 1300s.
More to the point, your basic francophone Lower Canadian fur trade employees — the majority of non-locally born folks out here until the 1840s or 50s — grew up calling a British sixpence “quinze sous”.
I don’t know why they’d call a river this. If it’s the relatively minor Newaukum, maybe the idea is of a piddling little stream? Sixpence would be like an American nickel.
At any rate I believe we have here a “stealth” trace of Hudson’s Bay Company influence. Recall that quite a few of the major landscape features in our region have old Canadian French names, including the Dalles (Oregon), Boistfort (Washington), Coeur d’Alene (Idaho), all of our Coulees and Portages, and so on.
Regional history expert Edmond Meany’s book “Origin of Washington Geographic Names” made a rare mistake with this place name (1923:239-240). He recorded it as the “Quinze River”, due to unquestioningly copying a mere (but typical) punctuation mistake from the 1800s. He quotes British spy (read the work of Jack Nisbet) Mervin Vavasour from 1845:
This route, or portage, as it is usually called, passes through small plains …, crossing the Quinze, Sous, Vassels , Chute , and Nisqually Rivers…
See that stray comma? Meany’s book doesn’t list any separate “Sous” River! If he had, and had investigated Vavasour’s quote a little more, he would probably have realized his slipup.
Some language-related footnotes:
 Er, Newaukum is Chehalis Salish for ‘big prairie’!
 The Skookumchuck (Chinuk Wawa skúkum tsə́qw ‘swift water; rapids’).
 Deschutes ‘Of The Waterfalls’, cf. the town of Tumwater, WA (təmwáta ‘waterfall’ in Chinuk Wawa), on it.