Champoeg & sand & water?

Champoeg school, circa 1860 (image credit: Pinterest)
Please categorize today’s post among my more purely speculative ones; it’s about chámpʰúyk, as it’s known in Jargon…
This Oregon place was named something like Champoeg (as we now spell it on maps) in the Indigenous K’alapuyan language.
I’ve done much less linguistic work on K’alapuyan than on other Native languages of the area, but I recognize the ‘place of’ prefix cha(m)- there. You find it also in Chemeketa, Chemawa, and Chachalu, which is the museum and culture center of the Confederated Tribes of Grand Ronde.
In its entry about chámpʰúyk, the 2012 Chinuk Wawa dictionary by CTGR helpfully points to a known K’alapuyan noun form -búičuk for the yampah / Indian carrot / Perideridea species.
I agree with them that this is the best etymology we have for Champoeg.
I will muse on this a little more, however. In line with Henry Zenk’s highly recommended article, “Notes on Native American Place-Names of the Willamette Valley Region” (Oregon Historical Quarterly 109(1):6-33, Spring 2008), we can note that the etymology of the name Champoeg is not entirely clear.
The location was known to the early frontier-era Canadian / Métis French-speaking fur trade as “Sandy Camp”. More French influence is possible in the common pronunciation “Shampoo-ee”, as Henry Zenk notes; my understanding is that many, or most, French words that originally had a “k” sound at the end have lost it.
This French expression is what we see in Father Modeste Demers’ 1839 report to his bosses back home in Québec, when he refers to “au campement du sable (Tcham-poneh)“.
(Also see ethnohistorian David G. Lewis’ fine work on the “Location of the Campement du Sable“.)
The last word’s spelling as Tcham-poneh brings to my mind Chinuk Wawa’s púlali ‘dust, powder’. Because there’s this frequent alternation between “L” sounds and “N” sounds in regional languages, pul and < pon > amount to a possible exact match.
Granted, here we may be seeing nothing more than a typesetter’s mistaken way of spelling what could’ve been Tcham-poueh in the handwritten text they were working from. So take the following with a grain of salt.
I also think how similar the meaning of the related CW phrase púlali-ílihi ‘sand’ (literally ‘powder-earth’ and/or ‘powder-place’) is to campement du sable. Assuming the location is a sandy one, might its original K’alapuyan name have referenced that fact?
Using the book of “Kalapuya Texts” collected by Melville Jacobs as my data source, I find that ‘dust’ is a-sgúb / a-sk’úp and ‘powder’ is a-mánqt. I find no word for ‘sand’, but there remains a theoretical chance that the word for it is something like *a-púyk, as we might guess if champʰúyk came from a word for ‘sandy place’. So there you’d have a hypothetical etymology for the place name.
But a further wrinkle is that Champoeg was not necessarily the same exact place as the Campement du Sable. They may have been as much as a few miles apart, Lewis finds. And Zenk shows (pages 14-15) that any known K’alapuyan word similar to Champoeg is still an imperfect match for that sequence of sounds; there’s a known placename nearby, cha[-]chíma[-]búichuk, ‘place (in front of?) yampah’ which is both pretty close and pretty far from explaining Champoeg!
So I’m going to boldly throw forth my sheer speculation. What if cha[-]chíma[-]búichuk indeed is the source of Champoeg — but only due to some kind of twist?
It’s not hard for me to imagine the non-Indigenous folks who hung around the area giving a folk-etymology to that K’alapuyan word, for instance. Could they have heard chachímabúichuk as a partly Chinuk Wawa chachímabúi[-]chə́qw, i.e. ‘chachímabúi-water / stream’, perhaps applying it to Mission Creek?
Such a cognitive development would then make possible an assumption by the Jargon-speaking newcomers that chachímabúi is the name of a place on or near that river. A place such as Champoeg.
The same non-Native people could conceivably have collapsed the repetitive-sounding first 2 syllables (chachi…) into 1 (cha…). Or, having heard plenty of K’alapuyan spoken, they could have spotted the prominent K’alapuyan locative prefix cha- for what it is, and removed it, leaving chimabui. Either of these supposed developments, or both, would result in something sounding very much like the modern “shampoo-ee” pronunciation.