If you haven’t seen it elsewhere, it is probably because it isn’t true. The dams have cut the avg flow by about a third, but both rivers are variable, just like every river on Earth, including the Amazon. The story appears to be either agitprop or some other kind of fake, or based on something that happened over twenty years ago.
> Turkey’s Ataturk Dam was completed in 1990. It is the largest of a series of dams along the two major rivers of the region, the Tigris and Euphrates, which both have their headwaters in southeastern Turkey. Built both to generate electricity for the region and to irrigate the plains between the Euphrates (on which it sits) and the Tigris (to the east), Ataturk Dam is the centerpiece of a huge public works program within Turkey known as the Southeastern Anatolia Project. When the entire program of reservoirs, power generation stations, and irrigation channels is constructed, it will irrigate some 1.7 million hectares (4.2 million acres). The reservoir already provides 8.9 billion kilowatt hours of electricity, roughly 22 percent of Turkey’s anticipated electrical needs in 2010, when the project is expected to be completed.
http://visibleearth.nasa.gov/view.php?id=3796
> the upfilling of the reservoir was completed in 1992
http://en.wikipedia.org/wiki/Atat%C3%BCrk_Dam
There is a link in the source article to a NRO article by Daniel Pipes reporting June 2nd.