The problem arises when your claim to naturally occuring things necessary to sustaining life, like rocks, water, and wild plants and animals, interferes with my right to naturally occuring or man-made things necessary to sustaining life. In its natural, primitive state, people living along the unmodified Nile could trot down to the river to get a drink, but this doesn’t sustain the 30 million people living in the 6.6 K square miles making up Cairo. Part of life is recognizing that very many people – like, all people – have a reasonable interest in those natually-occurring resources. Thus, the Egyptians have a right to impede the flow of the Nile for their purposes, the Sudanese do to, likewise the Ethiopians, South Sudanese and Ugandans. Also Kenya and Tanzania, because both nation border on Lake Victoria, which feeds the White Nile.
I agree that when there are such shared natural resources, agreements based on facts, reason and the rights of everyone involved are necessary. We should presume that the parties involved differ in their opinions about their “rights”, and what the facts are, so this is not a matter that will in fact be solved by reason. Still, if we cannot figure out some rational principle that adjudicates there matter, we really can’t expect them to do a better job.
It seems to me, based on your statement about the right to life being paramount and impeding established travel route being less important, that you have some kind of immediacy-based theory of the right to life. Travel, agriculture, drinking water, industry are all necessary for man’s survival qua man. Drinking water is immediately necessary, on the order of 3 days, compared to 3 weeks for food. That would suggest that if a man has a right to drink that water, and another man has the right to use that water to grow crops, the farmer must sacrifice his right in favor of the man with a superior right to immediate drinking water. But only according to the objective needs of slaking his thirst. If that is not what you mean, then what is the point of implying that navigation is a lesser right than drinking?
Based on the nature of water usage, hydroelectric is arguably a “superior” usage by right, because it does not contradict another man’s right to use the water for drinking. Drinking up the water or using it to grow food takes it out of the river and makes it not available for hydroelectric (or anything else). From this, we should conclude that Ethiopia has a superior right to use the water that flows through it, because that water can then be used by Egypt to drink, farm, manufacture, and transport. Now, also bear in mind that drinking water is a minor use of the river by Egypt. What is the proper hierarchy of usage rights for water – drinking, irrigation, flood control, transportation, manufacturing, hydroelectric? Which necessities of life are most dispensible, which then determine what right others living along a river may do? Just because Egyptians drink some of the river, does that mean they may rightfully veto Ethiopian use of the water?
The question of who built the dam is a red herring: they (the Aswan dam and theGrand Ethiopian Renaissance Dam) are both the product of government confiscation, just like Grand Coulee and Hoover dams in the US are.