[bilbo0s]

I read that as the British left a mess by allocating 70% of Ethiopia's water to Egypt even though the British had no legitimate claim or control over Ethiopia.

Though even if the British had been in control of Ethiopia, I would argue it was still problematic to allocate 70% of their water to Egypt. It was just a fundamentally bad arrangement. So fundamentally bad that I can only assume the British, at the time, had no idea how the Nile actually worked. Maybe the field of hydrology was not quite so well developed, and the Nile was not quite so well studied? I try not to attribute to malice what can reasonably be explained by ineptitude.