UNITED NATIONS (Reuters) – The United States and Iraq on Wednesday hosted a meeting of senior diplomats and U.N. officials to discuss the possible collapse of the Mosul hydro-electric dam, which U.S. Ambassador Samantha Power said would create a catastrophe of “epic proportions.”

Mosul dam has sustained structural flaws since its construction in the 1980s. If it collapsed, a wall of water would flood the heavily populated Tigris River valley.

Wednesday’s meeting at the United Nations included Power and her Iraqi counterpart, Mohamed Ali Alhakim, experts from the U.S. Army Corps of Engineers, officials from the U.N. Development Program and Office for the Coordination of Humanitarian Affairs, and other senior diplomats.

“The briefings on the Mosul dam today were chilling,” Power said in a statement issued by the U.S. mission to the United Nations. “While important steps have been taken to address a potential breach, the dam could still fail.”

“In the event of a breach, there is the potential in some places for a flood wave up to 15 yards high that could sweep up everything in its path, including people, cars, unexploded ordnance, waste and other hazardous material, further endangering massive population centers,” she said.

Power said all U.N. member states should be prepared to help prevent what would be “a humanitarian catastrophe of epic proportions.”

Approximately 500,000 to 1.47 million Iraqis live in the flood path, the U.S. statement said.

Iraq has signed a contract with Italy’s Trevi Group worth $296 million to reinforce and maintain the Mosul dam for 18 months.

Italy has said it planned to send 450 troops to protect the site of the dam, which is 2.2 miles long and close to territory held by Islamic State militants.

Islamic State militants seized the dam in August 2014, raising fears they might blow it up. It was taken two weeks later by Iraqi government forces backed by U.S.-led coalition air strikes.

The Iraqi government has said it is taking precautions against the dam’s collapse, while seeking to play down the risk.

(Reporting by Louis Charbonneau; Editing by Toni Reinhold)