How does water from the Columbia Icefield reach the Mackenzie River?

Water from the Columbia Icefield reaches the Mackenzie River through a specific drainage path originating at the Athabasca Glacier.

Meltwater from this glacier flows into the Athabasca River, which travels northeast across Alberta to Lake Athabasca. From there, the water continues through the Slave River and Great Slave Lake before entering the Mackenzie River system, eventually flowing northward into the Arctic Ocean.1