Historic Hood River
We’re told this image is circa 1900 and shows a Stanley Smith Lumber Company flume, which places it somewhere on the westside of the Hood River valley. They had flumes running from Rainy, Black and North lakes down to Greenpoint (Kingsley) and then on down to the Belmont and Ruthton mills.
This area of forest (if we can call it that) seems to have had a major fire. I suspect this is just east of Greenpoint, but that’s just a guess.
This looks more like a roller coaster than a flume. Perhaps it’s the end of this flume, given how it seems to widen and decrease in slope. It also looks like there is a trip gate a little ways up the flume. A trip gate lets the flume operator divert the flow if something goes wrong, so the water goes someplace where it can be managed with less damage while they repair the problem.