The New York Times reports: More than 16 months after Iraqi and Kurdish forces reclaimed Mosul Dam from Islamic State fighters, the structure faces a new threat: the danger that it may collapse because of insufficient maintenance, overwhelming major communities downstream with floodwaters.

In the worst-case scenario, according to State Department officials, an estimated 500,000 people could be killed while more than a million could be rendered homeless if the dam, Iraq’s largest, were to collapse in the spring, when the Tigris is swollen by rain and melting snow. The casualty toll and damage would be much less if Iraqi citizens received adequate warning, if the dam collapsed only partially or if it were breached in the summer or fall, when the water level is lower.

Mosul Dam, which was completed in 1984 by a German and Italian consortium and is 30 miles upstream from the city of Mosul, has long been a maintenance nightmare. Before fighters from the Islamic State, also known as ISIL or ISIS, swept across northern Iraq in 2014, approximately 600 Iraqis worked at the dam.

Because the water was eating away at the gypsum base under the dam, Iraqi teams drilled holes in that foundation and filled them with a cement grout mixture. That work was carried out three times a day, six days a week.

The Islamic State controlled the dam for a little more than a week in August 2014, but its fighters did not damage the structure. After it was retaken later that month, however, many of the Iraqi workers never returned and the Iraqi government did not resume regular maintenance. The Iraqis also lost their usual source of grouting material, which was produced by a factory in Mosul, now under the control of the Islamic State. [Continue reading…]