Of all the natural resources necessary to ensure human health and civilization, water is one of the most important. The United States is fortunate to be able to call itself a water-rich nation, yet conflicts over water are growing. Taken for granted when supplies are plentiful, water is the focus of increasing controversy as supplies now appear to be inadequate to meet demands in many areas of the country. The growth of population and industry, resulting in increased water demand, is one aspect of the problem, but actual physical scarcity of water is not the key issue in most regions. Rather, conditions of economic scarcity seem to prevail: there is enough water to meet society's needs, but there are few incentives for wise and conservative use of the resource or for effecting an efficient allocation among competing demands.