Corrosion is a huge, ever-present problem plaguing oceanographic engineers, ship designers, mariners, operators of desalination plants, petroleum companies with offshore facilities, and, in fact, everyone who places structures in salt water to do useful work. While the basic mechanisms of corrosion are known, there are many detailed aspects that are not: For example, the precise role of bacteriological slimes in causing corrosion on supposedly protected structures. Radioisotope tracers now are helping engineers follow the chemical, physical, and biological actions in corrosion processes. Fresh Water from Seawater In 1960 the chairman of the board of a large U. S. corporation made a fundamental policy decision for his company: Since the greatest critical need of man in the next decade would be fresh water, his company would begin working to produce large volumes of fresh water—including the development of methods for desalting seawater. His pioneering analysis proved to be prophetic. Throughout the world, more people are using more water for more purposes than ever before. Many areas of the world, including some that are densely populated, have been parched since the dawn of history. In others where water was once abundant, not only are natural sources being depleted faster than they are replaced, but many rivers and lakes have been so polluted that they can now scarcely be used. The world’s greatest resource of water is the ocean, but energy is required to remove the salt from it and make it potable or even useful for agriculture and industry. The energy produced by nuclear reactors is considered economical in the large quantities that soon will be required. The AEC and the Office of Saline Water of the Department of the Interior, after a preliminary study, have joined with the Metropolitan Water District of Southern California and the electric utility firms serving the area, to begin construction of a very large nuclear-power desalting plant on a man-made island off the California coast. The plant, when completed in the 1970s, will have an initial water capacity of 50 million gallons per day and also will generate about 1,800,000 kilowatts of electricity. Additional desalting capacity is planned for addition later to achieve a total water capacity of 150 million gallons per day. [Illustration: _Plans to construct a nuclear desalting plant in California were announced in August 1966 by (from left) AEC Commissioner James T. Ramey, Secretary of the Interior Stewart L. Udall, Mayor Samuel Yorty of Los Angeles, and Joseph Jensen, Board Chairman of the Metropolitan Water District of Southern California._] Plans for other nuclear-powered desalting projects around the world are being discussed by the United States government, the International Atomic Energy Agency and the governments of many other nations. Some of these also may be in operation during the early 1970s.[17]