Mackenzie River
At , the Mackenzie River drainage basin encompasses nearly 20 percent of Canada. About , or 54 percent of the basin, lies above Great Slave Lake. Permafrost underlies about three-quarters of the watershed, reaching up to deep in the Mackenzie Delta. As a whole, the Mackenzie basin receives only meager to moderate rainfall, averaging over the entire basin, though mountain areas experience much higher precipitation, and areas near and north of the Arctic Circle receive much lower precipitation.
Fraser River
The Water Survey of Canada currently operates 17 gauge stations that measure discharge and water level along the majority of the mainstem from Red Pass just downstream of Moose Lake within the Mount Robson Provincial Park to Steveston in Vancouver at the river mouth. With an average flow at the mouth of about , the Fraser is the largest river by discharge flowing into the Pacific seaboard of Canada and the fifth largest in the country. The average flow is highly seasonal; summer discharge rates can be ten times larger than the flow during the winter.