Egypt's foreign minister, Mohamed Kamel Amr, flew to Addis Ababa on Sunday, heading a delegation of diplomats, lawyers and engineers to pursue a troubling dispute over water.
Access to fresh water is becoming a pressure point in many places around the world, and the basin of the River Nile has become a prime example of the tensions that can arise.
The Blue Nile, the principal tributary of the mighty Nile, is the site of Ethiopia's planned Dh17 billion Grand Renaissance Dam. By 2018, when it is to be completed, this structure will generate 6,000 megawatts of power, almost three times as much as Egypt's Aswan Dam. Ethiopia aspires to be Africa's main exporter of electric power.
The problem is that in filling the reservoir behind the dam, Ethiopia will need to sequester 63 billion cubic metres of water, so much that the flow of the Nile, virtually Egypt's only water source, will be reduced significantly. Filling, supposed to begin in 2015, will take years.
Mr Amr and his team can expect a frosty reception in Ethiopia, after the amount of bluster that has come from Cairo. The Egyptian president, Mohammed Morsi, said last week that "all options are open to deal with this subject … If a single drop of the Nile is lost, our blood will be the alternative." And several Egyptian politicians, unaware that a camera was rolling, were caught last week speculating about covert or overt action to stop the dam. Calmer voices have pointed out that international disgrace would follow any resort to force, especially since Chinese and other foreign companies and individuals are at work at the site.
Still Mr Morsi, awash in domestic troubles, may be tempted to try the old trick of invoking a foreign enemy to rally his own people behind him. But Egypt's military will have little interest in adventures in Ethiopia.
Egypt's claim to the status quo is based principally on a 1929 agreement with Britain, but this has been overtaken by events: there are now 10 sovereign states in the Nile Basin, and the other nine signed a 2010 pact to develop the waters together.
Neither a faded and outdated treaty nor military force offers a solution to the current dispute. In the Himalayas and elsewhere, a modern legal framework and a robust arbitration system have been shown to serve to manage water disputes effectively.
The African Union and others have called on Ethiopia and Egypt to settle this problem peacefully and fairly. Despite the importance of the issue, reasonable compromise is surely not beyond the capacity of the two countries - provided that the will to compromise exists on both sides.