In an arid western landscape, rivers and lakes are often the source of all life.
Rivers harbor fish, amphibians and mammals that make their home in the water.
The riparian areas along the edges of rivers are home to many more species of mammals and birds, providing shelter, shade and a place to rest. Nearly all of the larger species of mammals make their way to the rivers at one time or another during the day to drink or bathe. This initiative helps protect and sustain Yellowstone's water resources. Yellowstone's aquatic system supports a large freshwater fishery that sustains one of the highest concentrations of blue-ribbon trout streams in the world. Yellowstone's streams, lakes, and wetlands support many biological functions such as migration, predation, nutrient flow, soil formation and human recreation.