For more than 30 years, water has been diverted from the Amu-Darya and the Syr-Darya Rivers feeding the Aral, to irrigate millions of acres of land for cotton and rice production in Central Asia. This has caused a loss of more than 60% of the lake's water. The lake has shrunk from over 65,000 sq km to less than half that size, exposing large areas of the lake bed.
From 1973 to 1987 the Aral dropped from fourth to sixth among the world's largest lakes.
The lake's salt concentration increased from 10% to more than 23%, contributing to the devastation of a once thriving fishery. The local climate has reportedly shifted, with hotter, drier summers and colder, longer winters.
As the water retreated, salty soil remained on the exposed lake bed. Dust storms have blown up to 75,000 tons of this exposed soil annually, dispersing its salt particles and pesticide residues. This air pollution has caused widespread nutritional and respiratory ailments, and crop yields have been diminished by the added salinity, even in some of the same fields irrigated with the diverted water.
Landsat satellite data, acquired and archived by the U. S. Geological Survey over the decades, are used by resource managers to measure the Aral Sea's extent and rate of drying. Each Landsat scene covers an area 170 km north/south x 185 km east/west (106 miles x 115 miles).