Many summer river flows in Alberta have changed drastically over the last century, and the graphs below show various summer river flows in Alberta. The flow reduction further downstream in the South Saskatchewan river is even more severe. At Saskatoon, Saskatchewan, the flow has dropped to 20% of that at the beginning of the 20th century. Summer flows are very ecologically important, for such things as fish spawning and rearing, and riparian sustenance. They also provide water for human uses such as irrigation.