Lake Albert is a typical Rift Valley lake lying at an altitude of 615 m between two parallel escarpments, that on the western side rising abruptly to nearly 2,000 m above the water surface. The lake is about 150 km long, with an average width of about 35 km, and a maximum depth of 56 m within 7 km of the mid-western shore. The main inflow is at the south end via the Semliki River which comes from Lake Edward through the western edge of the great Ituri rain forest in Zaire, augmented by streams from the northern slopes of the Rwenzoris. On its course through the forest are several kilometers of rapids which are an effective barrier to faunal interchange between the two lakes. Most of the lateral inflows into the lake from the escarpments are seasonal and contribute very little, since their catchments are small. Owing to an accident of geological history, the overflow from Lakes Victoria and Kyoga, known as the Victoria Nile, originated by uptilting of the Victoria basin in the late Pleistocene and made its way via a previous river valley to a low point along the Rift wall to plunge over the Murchison Falls and to reach Lake Albert at its very northernmost end almost directly into the outflowing Albert Nile.

The water of the Victoria Nile is much less saline than that of Lake Albert. It has therefore been possible to demonstrate by conductivity measurements that even in times of floods the river water does not affect the lake beyond about 10 km from the north end. The Victoria Nile thus serves to maintain the level but has no other influence on the water of the lake except at its northern end though its rate of flow is considerably greater than that of the Semliki. The hydrology and ecology of the lake would have been different if the Victoria Nile had flowed into it near the south end, or alternatively, had joined the Albert Nile further north where it could have had no controlling influence on the level of the lake. In the latter event a small reduction in the rainfall in the Albert and Edward basins and thus a smaller inflow from the Semliki, could result in an excess of evaporation over inflow with a consequent fall in level and stoppage of the outflow. The level of Lake Albert is now maintained above the exit partly by the Victoria Nile which functions in the manner of the inflow to a constant level water still (Q, 10).