Snowmelt
Snowmelt can also affect how good and safe drinking water is.  Snowflakes collect air pollution as they fall.  Snow on the ground collects pollution from cars, farm animals, fertilizer, and other things.  The snowmelt collects dirt and other pollutants on the ground.  Pollution in snowmelt can be a larger problem than pollution in rainwater because the snow collects pollution all winter and then the snowmelt combines with the spring rain and releases it all at the same time.  Then it flows into streams and reservoirs where human beings get their drinking water.