Christian Fraser, BBC News 5 Oct 09;
Legend has it that Alexander the Great spent nine days searching for the miracle of Siwa.
Four days into the journey his men had run out of water. By the time they eventually stumbled across the oasis it must have appeared - as it still does - like a mirage out of the sand.
Today Siwa is a nine-hour drive from Cairo, across some of the most barren desert anywhere on the planet. It sits 18 metres below sea level, the main oasis surrounded by green desert islands where water naturally springs to the surface.
Beneath the sandstone is the Nubian aquifer an enormous - yet finite - supply of fossilised water that has flowed for thousands of years.
It fills the turquoise bathing pools in Siwa; one of them, "the spring of Juba", is so old it was mentioned by the Greek historian Herodotus who lived in the 5th Century BC.
So abundant is the water that within the oasis they grow over 120 different types of dates, some considered the best in Egypt. But the ancient caravan routes on which they once transferred their produce to market have now been replaced by a tarmac road.
It brings tourists, technology, growth and the sort of development that threatens delicate eco-systems. In the past 20 years the water, that once flowed naturally from beneath the rocks, has been sucked at alarming rate from hundreds of man-made wells.
Mounir Neamatalla runs an eco lodge in Siwa, a hotel complex built with mud brick, a model of sustainable development. He is now fighting a lonely battle to preserve the unique Berber culture and the precious water reserves on which the oasis survives.
"Unfortunately the whole industry of well drilling is now very active in the oasis," he said, "to feed our greed and appetite for more.
"As a result the rate of natural replenishment of the springs is lower than it ought to be. We are competing with a natural phenomenon that has existed for thousands of years."
Abandoned fields
There are said to be five water companies bottling in Siwa, who use the remoteness of the oasis as a marketing tool. But they are only part of the problem.
The farmers, who had traditionally flooded their land with the water that flowed naturally from the springs, are also drilling for water from deep underground. It is estimated that are some 2,000 wells in an area of 35 sq km.
Suddenly there is too much water. The salt lake in the middle of the oasis - parts of which dried out in the summer - is slowly filling with fresh water pumped from man-made channels that border the farms.
The water emptied into the lake is drainage water that has run off the fields - it is wasted and once it has reached the lake is no longer usable.
On the eastern edge of the oasis we were shown abandoned fields and water storage tanks now full of saline water. It kills the land. Farmers say the water from the wells is deteriorating as the underground channels are drained faster than they are naturally replenished.
"This water was perfect some years ago. Now it is far too salty," says Omar Mohamed Abulesm, a local farmer.
"I am not allowed to drill for my own water but the government water which comes from the well in my field is killing my trees."
But in Omar's fields we discovered a makeshift pump hidden behind a bush. He has dug for his own water - his is one of hundreds of private wells that have been dug all over the oasis, that the government says are to blame.
Not too late
They have tried to limit private well drilling, replacing them with government wells that serve a number of farms. But the water that is pumped round the clock into the salt lake suggests their efforts are wasted.
They have tampered with a naturally balanced system - and they now require hulking great machinery to move water artificially into the lake.
"I don't say things are rosy," said Egypt's Fatma Abdel Rahman Attia who heads the Groundwater Sector in the Ministry of Water Resources and Irrigation. "But there are signs we are making progress.
"Remember that when you plug a well the water still finds a way to the surface through the limestone fissures," she added. "It is not always so straightforward.
"We are trying to control the drilling, it takes time, especially with the resistance of the local population. The best solution, we tell them, is to re-use that water that is feeding into the drains - so that what reaches the lake is the minimum."
But the local population blame the government for the problems and say they have offered solutions that are ignored.
The experts say it is not too late - but attitudes have to change.
Some believe Siwa could still be the example to the rest of the world on how to use and preserve a non-renewable resource.
"We should be revising our entire water management policy," said Mounir Neamatalla. "That requires research, to establish what level of development the aquifer will sustain, and it requires engagement and commitment at all levels."
Most known oases on the planet have long since vanished. Today Siwa might look like the bountiful paradise, there is water wherever you look, but who really knows how much of it is left below the surface?
From Siwa to Libya the Nubian aquifer is being drained at an increasing rate. And some believe without a more concerted effort by all parties, these green dots in the desert might suddenly and irrevocably disappear from the map.