Zooplankton surveillance cruises were conducted in April, May, June, and July 1980 in Lake Huron, including the North Channel and Georgian Bay. Rotifer standing stocks and species composition were indicative of oligotrophic to meso-oligotrophic conditions. Crustaceans were the numerically dominant zooplankton; this dominance was even larger when expressed in terms of dry weight. Crustacean standing stocks and composition also were indicative of oligotrophic to meso-oligotrophic conditions. Results of statistical analyses (correlation, principal components) provide information on water quality status as estimated from zooplankton population characteristics: such analyses include consideration of the physical-chemical properties of the water column. In addition; a phytoplankton: zooplankton carbon ratio was used to infer relative grazing pressure.