Mackenzie River Great Slave Lake, at Fort Resolution, Northwest Territories. The Slave is by far the largest river flowing into the lake, with an annual flow of 108 km (87 million acre-feet). It contributes about 77% of the overall inflow, and forms a large delta where it enters the lake. Other rivers entering Great Slave Lake area the Taltson, Lockhart and Hay Rivers, the latter of which also extends into Alberta and BC. The Mackenzie River issues from the western end of Great Slave Lake about south-west of Yellowknife. The channel is initially several kilometres wide but narrows to about at Fort
Lake Athabasca depth of , and holds of water, making it the largest and deepest lake in both Alberta and Saskatchewan, and the eighth largest in Canada. Water flows northward from the lake via the Slave River and Mackenzie River systems, eventually reaching the Arctic Ocean. Fort Chipewyan, one of the oldest European settlements in Alberta, is located on the western shore of the lake, where the Rivière des Rochers drains the lake and flows toward Slave River, beginning its northward journey along the eastern boundary of Wood Buffalo National Park. The eastern section of the lake narrows to a width of