Correct me if I'm wrong, but it looks like the Kazakhs are simply building a dike to claim what little will remain of the Aral for themselves.  With the damage of irrigation in place, the supply of water is what it will be, and the amount of evaporation that will balance that water supply is determined by climate.  The Kazakhs may be supporting their fishing industry, but I don't think the action should be heralded as a great blow for environmentalism...  it's really just more mucking around with the system.  And while Grist quips that the Uzbeks are not taking similar actions to save the southern portion of the sea, it's not at all clear that they have the option since the water supply to the souther (lower) section of the Aral come from the northern section, and are now going to be even smaller than it once was.