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
Petitot River Dene language of the Slavey First Nations is "mbehcholah", "The Black". It has a total length of and a drainage area of . Petitot River Petitot is a river in northern Alberta and British Columbia, Canada. It is a tributary of the Liard River. Petitot River originates from Bistcho Lake in northwestern Alberta, and flows westwards along the northern borders of Alberta and British Columbia. It then passes in the Northwest Territories, where it discharges in the Liard River at the village of Fort Liard. From there, its waters are carried to the Arctic Ocean through the Mackenzie River. The