Lake Victoria Maps

Lake Victoria is the biggest rain vessel in the world. It has the size of Ireland. All water falling within the brown envelope of the map below is in the Nile basin, essentially on its way to Egypt, the Mediterranean Sea, Gibraltar a journey of almost 6000 km, that is 1/7th of the circumference of the earth. But before running downwards, first it fills all depressions in the landscape. They become pools and lakes. Victoria Lake is such a rain water store, 1130 meters above sea level! When the rain fills the pool, it will eventually flow over somewhere. That turned out to be at Jinja, called by Speke the "source of the Nile". A romantic, but not too accurate name, because strictly, the rain.falling  within the area of the water shed forms that source. Jinja is just the overflow. There are no other overflows, nor places the would become and overflow if the Lake would rise several meters. Meanwhile in billions of years, the Lake has carved a deep trench for itself at Jinja, so it does not need any more overflows. Despite the construction of an electricity dam at Jinja, the Lake level went around one meter down in the past seven years.
It is not inappropriate to see the half of Uganda that is closest to the Lake as an archipelago of connected islands in a surrounding of a swamps generated by the rainfall within the Lake Victoria-Nile water sheds. At a slightly lower level two other big lakes, Kyoga and Albert, are depressions filled by this water, through the Nile and tributaries.