Lake Athabasca is in the north-west corner of Saskatchewan and the north-east corner of Alberta between 58° and 60° N in Canada. The lake is 26% in Alberta and 74% in Saskatchewan. The lake is fed by the Athabasca River and other rivers, and its water flows northward via the Slave River to the Mackenzie River system, eventually reaching the …Lake Athabasca is in the north-west corner of Saskatchewan and the north-east corner of Alberta between 58° and 60° N in Canada. The lake is 26% in Alberta and 74% in Saskatchewan. The lake is fed by the Athabasca River and other rivers, and its water flows northward via the Slave River to the Mackenzie River system, eventually reaching the Arctic Ocean.