Just a few miles down the road from the Denver siren in Toppenish is this one in Wapato, on the building which contains the city hall and former fire department. I don't know whether it's still in use. Sorry for the phone photo, but I didn't have a better camera with me.
Ah yes, I ran into that beast on my trip through there (the same one where I confused streets in Yakima and caused a stink over the hornless 'bolt). Was rather surprised to find it...everyone had presumed Toppenish was it as far as Denvers go in that area. Unfortunately I didn't bother to ask about it while I was there, and my photos have about much lighting on the siren as yours do...