 The water since at least 12,000 years ago drained across a natural rock weir.In 1952, engineers acting for the government of British Uganda blasted out the weir and reservoir to replace it with an artificial barrage to control the level of the lake and reduce the gradual erosion of the rock weir.A standard for mimicking the old rate of outflow called the "agreed curve" was established, setting the maximum flow rate at 300 to 1,700 cubic metres per second (392–2,224 cu yd/sec) depending on the lake's water level.