This paper reviews the current approach to source protection for the Great Lakes and the connecting channel municipal drinking water systems by the province of Ontario, Canada. Legislative requirements for technical reporting on vulnerability, source water issues and rating of drinking water threats are reviewed and some examples of delineations for zones of vulnerability about the raw water intake cribs and associated vulnerability scores are presented. General observations on source water quality and types of drinking water threats for the Great Lakes and the connecting channel water treatment plants in the upper and lower lakes are also provided along with an outline of next steps in the source protection process. Includes tables.