A new study from a research group at the University of Illinois at Urbana-Champaign (UIUC) and Lehigh University, led by civil and environmental engineers, have tracked water use taken from three of the most used aquifers in the U.S. Fresh water is, of course, becoming an issue in the U.S. as well as around the world as the population is expected to go from a little over the present 7 billion people to 9 billion people by 2050. Understanding how and where the water taken from all supplies, particularly those from the more major water sources such as these three aquifers, is vital for policy makers as they plan for the future. There are all sorts of tradeoffs that come with such decisions, and this is where politics will play the key role in deciding who gets what with our most precious resource. This involves where and how many people can settle in communities, agriculture, economies (both local and global), a huge variety of industrial uses, and transportation; all of these sectors of our society have large lobbies that will try to sway votes to their cause, so one can imagine the pressures decision-makers are under and will be under in the next couple decades.
Check out an article about the study here. There is a nice graphic that helps understand where the water goes. The published study can be found here. This is a good way to see another aspect of what engineers do.