WASHINGTON: With Earth’s inventory of clean, fresh water dwindling fast, scientists who once looked to the clouds are increasingly looking downward for new sources of the life-giving resource. What’s tempting them is a mysterious world of deep underground aquifers — huge rivers and lakes far beneath the surface, some of them containing “fossil” water as much as a million years old.

Recent mapping efforts suggest that some of these aquifers hold enough “blue gold” to support billions of people for centuries. But the lean and thirsty looks engendered by that enormous wealth of water have made some hydrologists, economists and political scientists nervous.

Little is known about the ecological impact of deep aquifer pumping, especially since it’s still not clear which of these sources are naturally refilled over time and which are true fossil aquifers — meaning they exist in sealed spaces much like oil reserves, available for one-time consumption and then lost.

Moreover, of the hundreds of water treaties and shared-use agreements forged by nations in recent decades, none applies to underground aquifers. With scores of major aquifers crossing international boundaries, the potential is rising for conflict and a greedy “race to the pumps.”

Only 2.5 per cent of the world’s water is fresh, and the vast majority of that is frozen in glaciers and icecaps. All told, less than three-tenths of one per cent of the planet’s fresh water is in the lakes and rivers that have served as the major sources of water through most of human history, and much of that is drying up or becoming spoiled.

“There are all kinds of signs that this level of use is not sustainable,” said Sandra Postel, director of the Global Water Policy Project in Amherst, Mass., pointing to falling water tables in many parts of the world. Already, about eight per cent of the food that feeds the world’s six billion people is being grown by taking water that is not being replenished. “If that’s the case now,” Postel said, “what are we going to do when we need to feed eight or nine billion people?”

One answer is to go underground, where there is 100 times the amount of water found on the surface — much of it at depths of a half a mile or more. —Dawn/LAT-WP News Service (c) The Washington Post