It is located in the wetlands of northern Alberta, adjacent to Highway 881, between Fort McMurray and Lac La Biche. It was known as Willow Lake Until 1940 when the name was changed to Gregoire Lake. In May of 1995 the name was changed back to Willow Lake by the Alberta Government.
The lake has a total area of 25.8 km2 (10.0 sq mi) and sits at an elevation of 480 m (1,570 ft). It has a maximum depth of 7.2 m (24 ft) and an average depth of 3.9 m (13 ft).