About 10% of the lake's water drains into the Fond du Lac River, which flows out of the lake to the north-west, where it drains into Lake Athabasca, which ultimately drains into the Arctic Ocean via the Mackenzie River system. The rest of the water drains into the Cochrane River, which flows out of the north-eastern side of the lake and into Reindeer Lake, which drains via the Churchill River system into Hudson Bay.[1]