About 80 percent of all the water we use in everyday life come from surface-water sources, such as rivers, streams, lakes, and reservoirs. The other 20 percent comes from ground-water. It is only natural that we heavily use our surface-water resources. After all, it is a lot easier and cheaper to get water out of a river than it is to drill a well and pump water out of the ground. Also, rivers are more accessible to us -- we generally build our towns and cities next to a river or lake.
The pie charts below show that for certain purposes, such as irrigation and supplying towns and cities with water, the United States relies heavily on surface water. Other users, such as mining and livestock industries rely more on ground water.
Information provided by: http://wwwga.usgs.gov