Saline Solution?

In his hasty attempt to deprecate the success of Russia's man-carrying spaceship, President Kennedy got lost in an old scientific daydream. Cheap fresh water extracted from salt water, he said, would benefit humanity enough to dwarf any other scientific accomplishment. This hope, that desalted sea water may make the deserts bloom as the rose, has long been popular. It has stirred speculative flurries on the stock exchanges; it can almost always get money out of Congress. Five big pilot desalting plants backed with federal money are now scheduled or already under construction. But the experts who came to the National Watershed Conference in dry-as-dust Tucson, Ariz., last week, knew better than to bother with such far-out schemes. Even the keynote speaker, Oklahoma Senator Robert Kerr, who mentioned grimly that U.S. cities now tolerate twice as much sewage in their drinking water as was considered safe in 1955, held out little hope that the situation would be eased by the use of sea water.

The conference discussed nearly every aspect of water supply--from underground storage to chaparral removal*--but no one voiced a hope that freshened sea water would soon solve the persistent problem of irrigation. The sad truth is that there is no such solution in sight. Sea water contains about 3% of salt, and there is a strong attraction between the salt and the water. A great deal of energy is necessary to break the bond. Dr. W. S. Gillam, research chief of the U.S. Office of Saline Water, recently estimated that the lowest possible cost of doing the job will never drop below 25-c- per 1,000 gal. No tricky process of freezing or distilling can reduce this figure. At present, none comes near it.

Farmers who depend on irrigation measure their water by the acre-foot (325,900 gal.): the amount that will cover one acre of land to a depth of 1 ft. At 25-c- per 1,000 gal., an acre-foot would cost more than $80--plus the cost of delivery from desalting plant to farm. Few farmers pay more than $5 per acre-foot, and most pay much less. Since practical water experts see little chance of cutting the basic $80 cost to $5, they hardly expect to see deserts made fruitful with desalted sea water.

Freshened sea water for municipal use is another matter. People in nearly rainless countries pay high prices for their drinking and washing water. Some oil refinery towns pay as much as $2 per 1,000 gal. ($650 per acre-foot) for distilled sea water, and a cut in the price would bring more desalting installations. But cities in well-watered regions are better off. New York pipes pure and plentiful water from the Catskill Mountains 70 miles away for 10-c- per 1,000 gal.--less than two-fifths the lowest possible cost of freshened sea water. No one in Tucson last week thought it likely that New-York would ever dip into the costly sea.

*Replacement of chaparral (Southwestern for brush) by grass improves water yield.

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