Water is an open-access resource, whose benefits can be enjoyed by many. This case on water use in America's breadbasket, the Great Plains, illustrates the "tragedy of the commons" in an international context. The case details water depletion in the Ogallala Aquifer, which lies beneath the Great Plains. At the same time, questions are raised about what constitutes optimal use of groundwater resources and what the role of U.S. agricultural and trade policy is or should be. This case is used in Darden's elective, "The Global Economics of Water." It would also work well in courses covering environmental sustainability or international economics.