Mackenzie River from the Peace-Athabasca system are significantly slowed by the delta area at the western end of Lake Athabasca causing the lake to rise, and the excess water can only flow out after the rivers have receded. The same phenomenon occurs at Great Slave Lake, which naturally regulates the flow from the Slave River into the Mackenzie. There are river gages at several upstream points along the Mackenzie River. The average flow rate at the outlet of Great Slave Lake is . At Fort Simpson, below the Liard River, it is . At Norman Wells it is , and at the
Turnagain River Turnagain River The Turnagain River is a river in the Canadian province of British Columbia. The Turnagain River was named by Samuel Black of the Hudson's Bay Company, who in 1824 journeyed to the river before turning back. Part of the river flows through the Muskwa-Kechika Management Area. The Turnagain River flows generally east and north to join the Kechika River. The Kechika River is a tributary of the Liard River, which is in turn tributary to the Mackenzie River, which empties into the Arctic Ocean. A notable tributary is the Cassiar River, which flows north to joins the Turnagain