It’s not just the Aral Sea that the communists almost destroyed; Lake Baikal in Siberia and Lake Sevan in Armenia had similar problems. Also remember the ludicrous Soviet plans to redirect Siberia’s north-flowing rivers southward to water Central Asia.
Maybe someone has written about this, but it always seemed to me that environmental activism is among the first cracks in a communist system, because it’s not strictly political, doesn’t necessarily have anything to do with the distribution of power or nationalist sentiments or religion or anything that would raise alarms among apparachiks. It was safe to talk about preserving the natural beauty of the socialist motherland; you’re seeing similar moves in China, I think.
Now, we saw environmental activism in the West at the same time, but in a democratic society there are self-correcting mechanisms, and so now we have cleaner air and water than we did a generation ago. But in a communist country, once people get away with criticizing institutions (even if only paper mills or smelters), they start to want to criticize other institutions as well, and pretty soon things start getting out of hand, dogs and cats living together, the whole thing.