This is widespread across much of North America, especially in cool slow calcareous waters (FNA 22, K). Also, it has become an invasive species in other parts of the world. The species is reported to be moderately tolerant of eutrophic conditions (Albert & Minc 2004, Croft & Chow-Fraser 2007). However, it has become rare to locally extinct in several east-central states with intense agricultural impacts on water quality (NS). The few scattered records from Ky. are mostly old or obscure. There is an old coll. from FAYE (MICH), made by R. Peter in 1834, from "lagoon, banks of Kentucky River below Raven Creek." During 2010, JC rediscovered it in FAYE at Lindsay Spring, on the edge of Lexington, growing mostly in cool water at a depth of 1-2 m.