YUSUFIYA, Iraq (Reuters) - What was known as history's fertile crescent, where lush farmland and abundant water gave rise to civilization, is today a dusty desert where the Tigris and Euphrates rivers crawl sluggishly toward the sea.
Vast tracts of Iraqi farmland are cracked and barren, precious marshes have dried up and sandstorms blot out the sun.
Even "Saddam River," the flagship drainage system Saddam Hussein launched in the 1980s to restore Iraq to its ancient agriculture glory, has turned into a sickly green stream flowing far below its high-water mark.
Such are the symptoms of a worsening water shortage that threatens to undermine Iraq's efforts to rebuild its economy after six years of war unleashed by the 2003 invasion.
Water is such a precious commodity in the arid Middle East that many experts predict water wars in the future if a sustainable solution is not found.
Tensions intensified earlier in the month when Turkey announced that it would resume work on its controversial plan to build a hydroelectric dam on the Tigris in its southeast.
Citing cultural and environmental standards, European backers have pulled support for the Ilisu dam project, a temporary victory for Baghdad, but Ankara is determined to push ahead as it seeks to wean itself off energy imports.
"This is not a new crisis for Iraq, but this time it's more serious than ever before," said Amro Hashim, an economic expert at Baghdad's Mustansiriya University.
Iraqi politicians are quick to blame upstream neighbors Turkey, Iran and Syria for dams and increased usage, but experts say Iraq's problems are also rooted in an exploding population, inefficient irrigation and few incentives to conserve water.
"It's everything going on at once. It's the urbanization, it's the climate change, short-term variability in climate, increased demand for food," said David Molden, deputy head of the International Water Management Institute in Sri Lanka.
"Iraq is one place, but it's not alone in the world ... Yes you can always blame neighbors or climate change but ultimately we've got to change the way water is managed," he said.
Iraq is now in the second year of a major drought, and last year's use of reserves has made for the worst water shortage in a decade, U.S. officials in Baghdad say.
Drought may bring one of the worst wheat crops in a decade, as low as 1.35 million tonnes or around half a normal crop, a dramatic reversal for a nation that was once a regional grains supplier but which now ranks among top world wheat importers.
It's not just a lack of water that has made Iraqi agriculture so anemic, says Salah Faisal, a farmer bracing himself for reduced harvest on his farm south of Baghdad.
"In the 1980s it was war with Iran, in the 90s it was Kuwait and now it's the Americans. There are 5-6 million martyrs and 70 percent of the people in the countryside have fled. What do you expect?" he asked, squinting beneath the scorching summer sun.
Trouble for Iraq's farm sector, the largest employer but dwarfed by oil in economic output, equals trouble for Iraq.
Dependence on food imports, depopulation of the countryside and a fear that idle youth may be recruited as insurgents are factors behind a special initiative launched by Prime Minister Nuri al-Maliki to revive the moribund farm industry.
Yet results will be slow as officials nudge farmers to abandon practices such as flood irrigation, which over time has boosted soil salinity and helped make farmland less fertile.
In the absence of proper drainage, Iraqi waterways are dangerously salty. The salinity level of water flowing into Iraq is 400 parts per million (ppm). When it reaches the Gulf, that has risen to 2,000 ppm, the Agriculture Ministry says.
That compares to around 1,000 ppm in the United States' Colorado river at its outfall, Molden said. "Most crops, except the most salt tolerant crops, will drop in productivity from their potential when irrigated with this water."
In Baghdad, mud banks sprouting fields of reeds now rise out of the slow-moving Tigris, a far cry from 20 years ago when schoolchildren took a swim in its swift currents at their peril.
Chronic shortages threaten drinking water supplies and sanitation and exacerbate public health problems.
Complaining of government inaction, lawmakers voted recently to block any deals with Iran, Syria or Turkey that do not grant Iraq a greater share of water. It was a largely symbolic move, but one that spoke of deep political disaffection.
"The government doesn't have political will," said Jamal al-Bateekh, a member of parliament's water committee. "It needs to leverage its ties with the United States to pressure Turkey."
Attempts to force the government's hand could undermine Maliki's efforts to improve fragile relations with Turkey, a key trading partner which has often been at odds with Baghdad over Kurdish rebels in northern Iraq.
There are growing complaints from Iraqi officials like Oun Thiab Abdullah, Iraq's water resources director, who doubts Turkish promises to guarantee a minimum of 400 cubic meters of water a second at the point where the Euphrates leaves Turkey and enters Syria before crossing into Iraq.
Abdullah said the river's water flow at that entry point had dropped in early July as low as 289 cubic meters a second.
"We are giving 515 cubic meters to Syria per second on average. This figure is consistent with our obligations," Taner Yildiz, Turkey's energy minister, said last week.
In a bid to reverse soil salinity and improve farm yields, the United States has spent at least $130 million to repair and extend the farmland drainage canal made famous under Saddam.
It rehabilitated a drainage pump station in southern Iraq, the Middle East's largest, that will send runoff farm water out to sea and, if managed properly, over time leach salt from soil.
Much more must be done to promote conservation in a country where farmers do not pay for water and many people in the capital go years without getting a single water bill.
A U.S. official in Baghdad, who requested anonymity, said the government must also embrace conservation as a priority.
"Should they start a policy of some of a market-oriented water management system where they charge for water? Probably, but it's not politically acceptable," the official said.
Improved methods such as drip irrigation are costly and require equipment and training most farmers don't now have.
"If we plant it, it dies off because there's not enough water and too much salt," said Abdul al-Salam Haider, who used to grow apricots, oranges and other fruit on his farm in southern Iraq. Now he doesn't even try.
"Iraq, because of its environment, is seeing these problems now, but a lot of other places on earth will see them in the future," Molden said. That is why, he said, "we've got to take a stand to figure it out in places like Iraq."
For an interactive factbox on water, please click on the link: here
(Additional reporting by Mohanad Mohammed, Aseel Kami and Khalid al-Ansary in Baghdad, Aref Mohammed in Basra and Selcuk Gokoluk in Ankara)
(Editing by Megan Goldin)