Start Here explains why Ethiopia's new dam on the Nile river has Egypt worried about its water supply being cut off.

Ethiopia has been building a new hydroelectric dam that is promising to revive its economy and bring electricity to millions of people in mostly rural areas.

But the Grand Renaissance Dam has its critics, mainly Egypt. It says its water supply is in danger, and its people depend on that flow for consumption and farming.

In the past, the two countries have made threats about military action and so far, talks to reach some kind of deal over how to share the Nile’s waters have not gone far.

So why can’t the two sides come to an agreement?

Start Here explains one of the most important disputes in Africa right now.