Egyptian president Mohammed Morsi on Monday warned Ethiopia that all “options are open” in dealing with its construction of a Nile dam that threatens his country's water supply, according to the BBC.
To make way for the Grand Renaissance Dam, Ethiopia has started diverting a stretch of the Blue Nile near its border with Sudan.
The river, one of the Nile's two major tributaries, contributes roughly four fifths of the Nile's flow, while the other, the White Nile, accounts for less than a fifth.
Upon completion, the dam will be 145 metres in height and stretch nearly 1.8 kilometres in length.
Experts estimate that filling Ethiopia's massive reservoir could cost Egypt as much as 20 percent of its Nile water in three to five years.
The building of the $4.7 billion hydroelectric dam, Africa's largest, challenges a colonial-era agreement giving Egypt rights to 90 percent of the Nile's water.