The dam was built on an unstable foundation that continuously erodes, and a lapse in maintenance after the Islamic State jihadist group briefly seized it in 2014 weakened the already flawed structure.
"All information gathered in the last year indicates Mosul Dam is at a signficantly higher risk of failure than originally understood," said the assessment from the US Army Corps of Engineers, cited in an Iraqi parliamentary report on yesterday.
Since the dam's completion in 1984, the Iraqi government has sought to shore up the foundation by injecting mortar-like grout into cavities that develop under the structure.
A US officer said the jihadists chased off the workers and stole equipment from the dam in 2014, but grouting has since been resumed.
"The reduction in grouting capacity for the past year has almost certainly resulted in an unprecedented level of untreated voids in the foundation from the continued dissolution and erosion of the geology," according to the US assessment, which was dated January 30.
In 2007, the US ambassador to Iraq and the top American military commander in the country wrote a letter warning that the dam could fail with devastating results.
"A catastrophic failure of the Mosul Dam would result in flooding along the Tigris River all the way to Baghdad," the letter said.
"Assuming a worst case scenario, an instantaneous failure of Mosul Dam filled to its maximum operating level could result in a flood wave 20 metres deep at the city of Mosul," it said.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
