Atrek

The Atrek, also known as the Attrack, Atrak, and Etrek, is a fast-moving river which begins in the mountains of north-eastern Iran and flows 563 kilometres (350 mi) westward, draining into the south-eastern corner of the Caspian Sea in Turkmenistan. Because of the high use of its waters for irrigation, the Atrek only flows into the Caspian when it is in its flood stage.