OhLook wrote in post #19466656
This seems to be what's called a flume here. My father did placer mining at one time in California. A flume was part of the local landscape.
Your father would have some interesting stories I imagine.
Flumes here were to my thinking different to that in my photo
Flume - the more artificial portion of a race or tail-race, consisting of piping, hose, or wooden boxes let into each other. Usually applied to wooden troughs for conveying water.
Water races such as in my photo were contained within a Water Race Reserve where they crossed private land.