With the appointment of a new government in Egypt and the death of Ethiopia's long-serving prime minister, Meles Zenawi, the emergence of new leadership in both countries presents opportunity for renewed dialogue and cooperation on Nile waters.
In 2005, the former UN secretary general and Egyptian foreign minister Boutros Boutros Ghali famously predicted that a future military confrontation over water rights was nearly inevitable. In 2005, Egypt's population was 75 million people. There are some 83 million Egyptians today. Ethiopia's population has similarly increased - from 78 million to 85 million in the same period.
No war over water is imminently probable. Yet even the colonial legacy that gives Egypt the bulk of the Nile's flow, and in the absence of a new consensus determines the share of Nile waters - treaties signed in 1929 and 1959 are still in effect, even though the signatories did not even consult Ethiopia or other upstream states - is not enough to meet Egyptian demand.
One of the stated objectives of Egypt's ministry of water resources and irrigation is to "increase Egypt's share of Nile water", admittedly not unilaterally, but "through cooperation and coordination with the Nile Basin countries". In this respect, at least so far, water policy in the new Egypt appears little different from that of the Mubarak era.
But Egypt has to reckon with upstream nations with ambitions of their own. Chief among these is Ethiopia, a country today transformed from that which Zenawi inherited in 1991. Notwithstanding his domestic policies, Zenawi's most far-reaching legacy for the region may be the aggressive development of Ethiopia's hydroelectric resources.
In southern Ethiopia, construction of the $2 billion (Dh7.3 billion) Gibe III dam on the Omo River is advancing. The dam is due to be completed next year, despite widespread concern over environmental effects that may jeopardise the livelihoods of half a million people and radically reduce the water levels in arid northern Kenya's most important lake, Turkana.
On the Blue Nile, which provides more than three quarters of the water that reaches Egypt, work has started on a project that dwarfs Gibe III. The Grand Ethiopian Renaissance Dam, about 40 kilometres from the border with Sudan, will create a reservoir of 65 billion cubic metres, about half the water volume of Lake Nasser, the reservoir of the Aswan High Dam in upper Egypt.
And as far as Cairo is concerned, the complications extend beyond Ethiopia. In the same week that Mohammed Morsi became president of Egypt, newly independent South Sudan was formally admitted as the 10th member of the Nile Basin Initiative, a multilateral organisation comprising all upstream and downstream countries in the Nile Basin: Burundi, Democratic Republic of Congo, Egypt, Ethiopia, Kenya, Rwanda, Sudan, Tanzania and Uganda.
Historically, Sudan and Egypt have opposed moves by the other Nile Basin countries to amend the colonial treaties governing Nile water. Evidently, the 1959 treaty did not foresee an independent South Sudan, and the implications for Juba's share of Nile waters.
Like most post-secession issues between Sudan and South Sudan, the South's allocation of Nile waters is not agreed. Nor is Khartoum, like Cairo before it, likely to easily give ground to a state upstream. The acrimonious relationship between Juba and Khartoum is unlikely to help.
Whether Egypt likes it or not, Ethiopia will build its dams. And the united front once shared with Khartoum against the other upstream states is unavoidably changing, with South Sudan now pursuing its own interests and policies, and perhaps one day its own mega-hydroelectric projects.
Now is the time for pragmatism, and recognition that decades-old agreements are no longer fit for purpose. Egypt's new prime minister, Hisham Kandil, is familiar with the challenges. A career water engineer who briefly served as minister of irrigation and water resources from 2011-2012 and as technical delegate to Nile Basin Initiative consultations, Mr Kandil has spent years thinking about these issues. Among the competing priorities in post-Mubarak Egypt, tackling Nile politics can't indefinitely be postponed. The Nile is not just a river in Egypt.
Aly Verjee is senior researcher at the Rift Valley Institute, specialising in the politics of eastern Africa