b44c1d7d8371fcf493e1b8df4bafd3ca

Went back to the location where I found a shell 2 years ago (http://www.inaturalist.org/observations/1953137) to look for more activity. Found 3 shells in a dried off creek that also acts as a park pond overflow. I suspect the snails were living in the pond not the creek, based on continual water supply, observance of a floating shell in the pond, and lack of any other mollusk activity in the creek.