McKay Lake (formerly Hemlock Lake, McKay's Lake, or MacKay Lake) is a meromictic lake located in the former Village of Rockcliffe Park in Ottawa, Ontario, Canada. The lake is named for Thomas McKay, one of the founders of Ottawa, who once owned all of Rockcliffe Park in the 19th Century, including the lake. The lake was officially named McKay Lake in 1954 after Rockcliffe Park Village Council passed a by-law. Prior to that the lake often appeared on maps as "Hemlock Lake", but locals referred to it as McKay Lake.