Osman Sagar popularly known as Gandipet, is a reservoir in the Indian city of Hyderabad. The lake is around 46 km², and the reservoir is around 29 km².HistoryOsman Sagar was created by damming the Musi River in 1920, to provide an additional source of drinking water for Hyderabad and to protect the city after the Great Musi Flood of 1908. It was constructed during the reign of the last Nizam of Hyderabad, Osman Ali Khan, hence its name.A princely guest house called Sagar Mahal, overlooking the lake and now a heritage building, was built as a summer resort of the last Nizam. Its location on the banks of the lake offers wonderful views. Telangana Tourism Department operates a resort in the building. The breeze of the lake is very pleasant and has been popular with the locals since the Nizam’s time.Tourist spotIt is a popular tourist destination, especially after the rainy season when the reservoir is full. Its parks, resorts, amusement park are a major attraction. This lake had served drinking water for Hyderabad city but, due to increase in population, it is not sufficient for water supply to Hyderabad city. Now it is used for public recreation.Water levelsIn June 2012, the water level at Osman Sagar was 1769.8 feet. On October 1, 2012, the level was 1771.8 feet, an increase of a mere 2 feet.Similarly, in nearby Himayat Sagar, the water level in June 2012 was 1743.3 feet and on October 1, 2012, it was 1,747.4 feet, an increase of about 4 feet. In October 2011, the water levels at Osman Sagar and Himayat Sagar were 1781.9 feet and 1754.9 feet respectively.