The dam is on the Tigris River, 45 miles north of the city of Mosul.
A catastrophic failure, engineers believe, could unleash a 60-foot-high wall of water that would be inundate Mosul - and flood Baghdad to a depth of fifteen feet.
The casualty count would be in the hundreds of thousands.
The United States has supplied $27 million worth of equipment to upgrade this aging machinery used for reinforcing, which has been a problem since it was built in 1984.
Nevertheless, a report to be released today says that because of potential erosion the Mosul Dam is "the most dangerous dam in the world."
The problem is that it was built on a type of rock that dissolves when it comes into contact with water.
In a telephone interview, the Iraqi minister of water resources admitted there were, in his words "some problems," but added that his ministry was "planning to design a permanent solution."
In spite of the Iraqi government's professed confidence, Ambassador Ryan Crocker and General David Petraeus sent a letter to the Iraqi prime minister in May stating that the damn presented "unacceptable risks."
Given that a break could trigger a flood of Biblical proportion, that may go down as a classic example of diplomatic understatement.