By Rayhan Demytrie
BBC News, Almaty

File photo of marooned ships near the town of Aralsk, 2005
The Aral Sea has shrunk by 90% in recent decades

The presidents of five Central Asian states are due hold a summit in the Kazakh city of Almaty about water, the most contentious issue in the region.

The annual forum includes all five founding members of the International Fund for Saving the Aral Sea.

Water is a precious resource in semi-arid Central Asia.

But since the Soviet Union’s collapse Central Asian states have failed to find a successful regional approach for its management.

Barter scheme

The five Central Asian leaders, who have a poor record on co-operation, will be debating the region’s most disputed issue.

Drought and overuse have caused an ecological disaster in the Aral Sea, which has shrunk by 90% in recent decades.

Upstream countries Tajikistan and Kyrgyzstan hold almost 80% of all Central Asia’s water resources in their mountains and reservoirs.

The three downstream states Uzbekistan, Turkmenistan and Kazakhstan need large amounts of water to irrigate their cotton and for other agricultural industries.

In Soviet times a system of exchange enabled the five states to share water and energy resources such as electricity and gas.

But the barter scheme is no longer active.

Tajikistan and Kyrgyzstan, which suffer most during cold winters, have long been pursuing the construction of hydropower projects in their territories.

Uzbekistan fiercely opposes these projects saying the construction of hydropower stations and new damns would reduce the flow of water for cotton irrigation.

Russia, which has an interest in regional water resources, has not been invited.