The Aral Sea, located between Uzbekistan and Kazakhstan was once the fourth largest lake in the world. Two port cities were located on it and 22 different varieties of fish could be found in the Aral. However, when the Soviet Union decided to boost cotton farming by constructing dams on the two large rivers that flowed into the Aral Sea, soil erosion and evaporation took its effect. By the 1970s twenty percent of the sea had diminished, by 1980 thirty percent had diminished, forty percent by 1990 and today ninety percent of the Aral Sea has disappeared. However, the Kazakh government pledges to reverse this effect, and return the sea to its former glory.