Atrek

The Atrek, also known as the Attruck, Atrak, and Etrek, is one of the Longest Rivers in Iran and is a fast-flowing river that originates in the highlands of north-eastern Iran and travels 563 kilometers (350 miles) westward until pouring into Turkmenistan's south-eastern corner of the Caspian Sea. Because its waters are heavily used for agriculture, it only flows into the Caspian when it is at the flood stage. The Atrek is 669 kilometers (416 miles) long and drains a 27,300-square-kilometer basin.

The river defines the boundary between Iran and Turkmenistan, beginning around 37°59′28′′N 55°16′29′′E when its tributary the Sumbar joins it; this helped keep the area closed during the Cold War years. A 1957 pact between Iran and the USSR grants equal rights to 50 percent of the water in the Atrek's border areas. The same deal applies to the Aras River, which is now part of Iran's border with Azerbaijan. Despite the fact that sturgeons congregate in the Caspian Sea along the Turkmen shore, they do not now migrate into the Atrek River due to low water levels and pollution. Sturgeons no longer spawn in Turkmenistan because the Atrek is the sole Caspian watershed river on the Turkmen coast.

Total Length: 416 miles