Strange Stagnicola

In Tyhee Lake, near Telkwa in the Bulkley Valley, there are freshwater snails belonging to the genus Stagnicola that are remarkable for their strangeness. Shells are very long, often turreted, and don’t really resemble any Stagnicola species. I presume that they are a (perhaps) environmental form of Stagnicola elodes, which most resembles the shell on the far left in the photograph (though not so slender). I recall that there are similar-looking snails in Dragon Lake (there are a couple in British Columbia but I mean the one near Quesnel). Is there “something in the water”?