Water is among the most abundant of all materials known to man. In all its various forms, water covers 75 percent of the earth\u27s surface. It is estimated that the total physical quantity of water on the earth is 326,000,000 cubic miles. This apparent abundance belies the true nature of the water resource as it relates to the needs of man. At any given point in time, only a rather minute portion of this vast quantity of water is found in those forms and locations which render it useful to man. This may be attributed to the fact that utility in water is perishable and the efforts of man to amend the hydrological cycle have been successful only to a limited extent
