The major ecological problem is that diversion of the Amu Darya and Syr Darya rivers for irrigation has shrunk the sea's surface area by approximately 60 percent, and its volume by almost 80 percent. In 1960, the Aral Sea was the world's fourth-largest lake, with an area of approximately 68,000 km² (volume: 1100 km³); by 1998, it had dropped to 28,687 km², and eighth-largest. Over the same time period, the salinity of the Aral Sea has increased from about 10 g/l to about 45 g/l.
In 1987, the continuing shrinkage divided the lake into two separate bodies of water, the North Aral Sea and South Aral Sea; an artificial channel was dug to connect them, but that connection was gone by 1999, as the two seas continued to shrink.
For financial reasons, the (much larger) South Aral Sea has been abandoned to its fate. As it dries, it is leaving behind vast salt plains, producing dust storms, and making regional winters colder and summers hotter. Attempts to mitigate these effects include planting vegetation in the newly exposed seabed.
As of summer 2003, the South Aral Sea is vanishing faster than predicted. The surface is now 30.5 meters above sea level (3.5 meters lower than predicted in the early 1990s), and the water is 2.4 times as salty as the ocean. In the deepest parts of the sea, the bottom waters are saltier than the top, and not mixing. Thus, only the top of the sea is heated in the summer, and it evaporates faster than would otherwise be expected. Based on the recent data, the western part of the South Aral Sea is expected to be gone within 15 years; the eastern part could last indefinitely.
In October 2003, the Kazakh government announced a plan to build a concrete dam separating the two halves of the Aral Sea, in order to raise the water level of the North Aral Sea and reduce its salinity.
The land around the Aral Sea is also heavily polluted, and the people living in the area are suffering from a lack of fresh water.
Former harbor in Uzbekistan: Moynaq