Water descends from the clouds, and forms rivers, lakes, and seas. It is delivered to the earth absolutely free, not in accordance with man-made specifications or orders but at the caprice of the elements. Hence man to realize fully the benefits of this incomparable and recurring resource must have full knowledge of its erratic occurrence before ways and means may be devised for putting water to beneficial use and for preventing it from doing harm. Water facts are essential for the effective and efficient utility of water.