For the municipality in Finland, see JuukaJuga is a genus of freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the family Semisulcospiridae. These snails are native to the rivers of the northwestern United States and adjacent British Columbia. Several species are endemic to isolated large springs in the American Great Basin.The most abundant and widespread species, Juga plicifera, attains a height of up to 35 mm.