Water security in Iraq was a serious issue for many years before the advent of IS.
Even before the current crisis,
overuse, pollution, and population growth had stretched the resources of the Euphrates River, the main source of water for 27 million people not just in Iraq but in Syria and Turkey, too.
"The control of water barrages and hydroelectric works have always been of great geostrategic importance in Iraq," says Matthew Machowski, a research fellow at Queen Mary University of London (QMUL).
Little wonder, then, that IS has taken strategic locations along the Euphrates in both Iraq and in Syria, where it has controlled the Tabqah Dam since early 2013.
Iraqi officials say that since IS's capture of the Ramadi dam in Iraq's Anbar Province last month,
water shortages have worsened.
IS has partially closed the dam, a move that has forced more water from the Euphrates into Habaniyah Lake. Provincial security officials warned recently that "dire consequences and an environmental catastrophe" would be "inevitable" unless something was done.
Iraq's southern marshes are on the brink of that catastrophe.