Our journey starts in the Alberta Rockies where snow-melt plunges off the alpine slopes to form the major tributaries of the South Saskatchewan River System. Local water supplies play a major part in the evolution of prairie settlement. Water from the river supports irrigation, livestock, energy developments and cities. Cropland has changed the interaction of soils and water. Runoff carries agricultural chemicals from farm fields to the river, degrading the aquatic ecosystem. The upland ecosystem responds to wet and dry years and erratic climatic events influence the intensity of pest and disease outbreaks. Studies of tree rings in the Cypress Hills clearly show that through the centuries, climate and river are intimately linked. To be successful, human activity must recognize and respect these links.