Recently our family was on an outing with some friends to Reed Canyon, the uppermost source of Crystal Springs Creek, and as usual, I was on the lookout for one of my favorite denizens of the local waterways. When we came to the dam and the viewpoints over the fish ladder I spotted a mussel shell on the downstream side. What I first mistook for the eroded outer surface of the shell turned out to be the shining inside. Just a shell, probably washed down from the lake above where they have been identified before (and see blog post here) but it was partially buried in the sediment in the manner of a live one, so it is possible that it was a resident at that location previously.
The particular freshwater mussel genus here (the particulars of the species involved are currently under taxonomic review) is Anodonta, or floater mussels, though I could not be really sure of the ID from this sighting. There is a population of another type, Margaritifera falcata, the western pearlshell, in the main stem of Johnson Creek, and also in the Willamette, but they favor faster flow and rockier bottoms and none have ever been located in Crystal Springs Creek. Anyhow, we saw one probable Anodonta in the first pool below the downstream side of the dam at the fish ladder at Reed Lake. It was probably washed down from the lake after expiring (these mussels only live ten to fifteen years, as opposed to the western pearlshell's 150+ year lifespan). Sorry, no photo- didn't have the telephoto lens with a polarized filter.
To see more about the life-cycle, ecological importance, and sheer beauty of western freshwater mussels please see these links:
Xerces Society PNW mussel book
OregonLive mussel article
2017 Freshwater Mussel Rescue and Relocation