Egypt faces destabilization as it stands to lose much of the Nile water that is its lifeblood. Ethiopia's development plans depend on an ambitious multi-dam program announced in 2011.
Cairo describes this as a threat to Egypt's national security, heightening tension in the escalating battle for control over the world's longest river.
But the wave of domestic turmoil that has gripped the Arab world's most populous nation since the February 2011 overthrow of longtime dictator Hosni Mubarak, has pushed the Nile problem onto Cairo's back burner.
It's likely to be thrust even more to one side amid the tumult unleashed Nov. 23 when Mubarak's Islamist successor, President Mohamed Morsi, decreed himself near-absolute powers and immunity from legal oversight. His surprise move triggered nationwide protests and accusations he was becoming a dictator like Mubarak.
Morsi flew to Addis Ababa in July, soon after he became president, seeking to negotiate a settlement to the Nile dispute.
His two-day visit was a milestone in the stormy relations between the countries but Ethiopia's strongman, Prime Minister Meles Zenawi, reportedly refused to compromise on his plan to spend $12 billion on hydroelectric projects on the upper reaches of the Nile intended to produce 40,000 megawatts by 2035.
Zenawi's death Aug. 20 hasn't apparently led to any shift in Ethiopia's position even though the country, one of the world's poorest, has also been roiled by political upheaval itself following Zenawi's death.
About 13 percent of construction on the 6,000MW Grand Renaissance Dam has been completed.
With Egypt's ongoing revolution producing new violence, the worry is the Nile issue may not be addressed as a priority issue, as has been the case for some time -- or even that Morsi may use it to divert Egyptians' attention from his controversial power-grab.
Either way, the problem can only get worse.
"It's an oversight that could come back to haunt every stakeholder," the National newspaper published in the United Arab Emirates warned as far back as April, referring to the other African states through which the Nile runs on its way to the Mediterranean.
In an editorial headlined "A political crisis is a poor time to negotiate water," the daily observed: "Egypt is not the only country that depends on the Nile as the lifeblood of agriculture."
Uganda, Kenya, Tanzania, Rwanda, Burundi and the Democratic Republic of Congo, along with Ethiopia, signed an agreement to overturn British-colonial-era agreements dating to 1929.
These gave Egypt and Sudan 90 percent of the Nile's water flow and the power of veto over dam-building, even though 85 percent of the river's water flows from the Ethiopian highlands.
The Blue Nile merges with the White Nile at Khartoum, Sudan's capital.
Ethiopia and the upstream states contend they need more water because of burgeoning populations, industrialization and agricultural projects.
Under Mubarak, Egypt refused to negotiate. Morsi may be more pragmatic, as his July visit to Addis Ababa suggests, but Egypt has little wiggle room since it depends on the Nile for virtually all of its water.
It already has problems providing water for its 82 million people, a population that's expected to increase sharply in the years ahead.
"Even direct military action by Egypt cannot be ruled out," U.S. global security consultancy Stratfor observed recently.
"Cairo fears that once the dam is completed ... it will take two to three years, depending on rainfall, to fill up the 67 billion cubic meter reservoir, which could reduce the amount of water that flows into Egypt by 25 percent.
"After the reservoir fills up, there is no guarantee that Egypt will maintain its present share of the water."
Documents released by WiliLeaks in September 2011 said the Egyptian and Sudanese governments had planned to attack the Grand Renaissance Dam. Egypt denied that.
Stratfor said direct military action "was the least likely approach and one Cairo would undertake only if the dam was completed.
"Such a course will also largely depend on Egypt's new leadership ... but whatever its political inclination, a large-scale reduction in water from the Nile would be intolerable to any Egyptian government."