Lake Manchar is the largest freshwater lake in Pakistan and one of Asia's largest. It is located west of the Indus River, in Dadu District, Sindh. The area of the lake fluctuates with the seasons from as little as 350 km² to as much as 520 km². The lake collects water from numerous small streams in the Kirthar Mountains and empties into the Indus River.
The lake was created in the 1930s when the Sukkur Barrage was constructed on the river Indus. The lake is fed by two canals, the Aral and the Danister from the river Indus. Until recently the lake supported thousands of fisherfolk, near village Kot Lashari Bobak railway station,who depended on the freshwater fish they caught in the lake. However, the lake is now undergoing environmental degradation resulting in the water becoming saline and killing off the fish and forcing the fisherfolk to look elsewhere for employment.
The degradation has been occurring for a long time but only recently have the effects been felt. The diversion of water from the Indus and a diminished storm runoff from the Kirthar mountains have contributed to the reduction in fresh water supplies. At the same time, saline drainage water from agricultural fields in surrounding areas has started to flow into Lake Manchar.
The lake was a stop-off on the Indus flyway for Siberian migratory birds, but recently the numbers have fallen from 25,000 birds counted in 1988 to just 2,800 bird counted in 2002, because the lake no longer provides the birds' main food, the lake fish. In the place of the birds, the lake now hosts a saline water reed.
The lake also provided large volumes of water for irrigation but this has also been reduced and has resulted in a great reduction in the area irrigated by the lake.