Crawling Water Beetles lack strongly flattened legs, rather appearing to "run" through the water with all six slender legs.
For identification of haliplids from eastern Canada, see:
Ashbee, H.V., Marshall, S.A., and Alarie, Y. 2017. Haliplidae of Eastern Canada. Canadian Journal of Arthropod Identification, 32. doi: 10.3752/cjai.2017.32. Available from http://cjai.biologicalsurvey.ca/ama_32/ama_32.html