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
Christina Lake (Alberta) River at its western end. The Jackfish River flows before it empties into the Christina River, a tributary of the Clearwater River. The waters eventually reach the Arctic Ocean via the Athabasca and MacKenzie Rivers. Christina Lake and the Christina River were named to honour Christine Gordon, originally from Scotland, who was the first white woman to live permanently in the Fort McMurray area, where she remained until her death in the 1940s. She was highly respected by the community, including the First Nations and Métis. Gordon, partly based on knowledge gleaned from a Scottish home nursing book, made her