In this module, which extends over two weeks, we will explore issues related to water use and scarcity. Major population centers and their burgeoning water needs, particularly those cities located in arid or semiarid regions with sparse local water supplies—Las Vegas, NV and Los Angeles, CA come to mind as glaring examples. In both of these cases the main source of water is surface water from distant sources, and we must examine the provisions and history of the Colorado River Compact to understand how water is allocated in the southwestern U.S. Later in this module, we will see how climate change can affect the Colorado River resource. New York City, on the other hand, is located in a region replete with surface and groundwater resources; but the NYC story is of interest because of the incredible planning and engineering that has gone into—and continues— assuring a steady water supply.
But cities are not the main consumers of water, as we have learned. We must also consider the impact of agriculture on water resources; in the U.S. this is, perhaps, best exemplified by the impacts on the huge multistate Ogallala Aquifer system of the Midwest, which has experienced considerable overdraft, primarily as the result of water withdrawals for crop irrigation. This will also serve as one of our water supply foci in this module.
We will also briefly examine how water is regulated. We have, of course, already covered (Module 7) regulation of drinking water quality, but it is equally important to understand who controls water allocations and how. Water resource allocations are much more complicated, with regional variations in water law and the additional impacts of regional and international compacts. Yes, there have been water "wars" (disputes) related to these laws/doctrines/principles, but we will not cover those here to any extent.
In this module our approach will differ from previous modules in that we will provide some background information on the major topics, including key illustrations, but will ask you to carefully read chapters in "The Big Thirst" (our "textbook", remember that?) and a few other articles, and to compose several short essays in answer to questions in the module.