The Lake Victoria has many tributaries from the countries of Rwanda, Tanzania, Kenya, and Uganda with River Kagera as the main tributary. The lake which covers about a third of the basin area greatly influences the outflow due to storage and regulation with the average annual outflow of 33BCM. There is not much variation of the flow from the mean since there is high regulation of the lake. Rainfall and Evaporation over the lake plays an important role in the water balance of the lake and also has an impact on the outflow from the lake.