The quarrel is over the rate at which Ethiopia fills the reservoir behind the dam and its effect on water supplies downstream in Sudan and Egypt--for who the Nile is the primary water source.

On and off since construction started, Egypt has threatened to go to war to secure continued access to the Nile waters.

If Egypt attacked Ethiopia, the antiquated idea that the Nile is a common good to which all have natural rights would collapse.

The Nile has two major tributaries--the White Nile is the headwaters and primary stream of the river, and the Blue Nile, containing 80 per cent of the water and originates in Ethiopia.

For now, Uganda should be able to collect custodian's fees from South Sudan, Sudan, Ethiopia and Egypt, and invest it in protecting the polluted Lake Nalubaale from which the Nile flows, and the real estate of the river that sits on its territory as it flows north.