Yeasts were isolated from lakes in northern Saskatchewan, from the Saskatchewan River between Prince Albert and Cumberland House, and from three small lakes near Saskatoon, two of which form part of recreational areas. Yeast and bacterial counts were relatively low, less than 400 yeast cells/liter, except in samples taken near towns and industrial plants which discharged waste into the rivers or lakes. There was little change in the numbers of yeast cells in waters used for recreational purposes only, but the number of species isolated increased considerably. Most of the yeasts isolated from the other lakes and rivers were species known to occur in association with trees and in soils.