Nanasaheb built a lake in Katraj, on the city's outskirts, and a still-operational underground aqueduct to bring water from the lake to Shaniwar Wada. The city received an underground sewage system in 1782 which discharged into the river. Pune prospered during Nanasaheb's reign. On the southern fringe of the city, he built a palace on the Parvati Hill, developed a garden known as Heera Baug, and dug a lake near the hill with a Ganesha temple on an island in its centre which is called Sarasbaug. Nanasaheb also developed new commercial, trading, and residential localities: Sadashiv Peth, Narayan Peth, Rasta Peth and Nana Peth. During the 1790s, the city had a population of 600,000. In 1781, after a city census, a household tax (gharpatti) was levied on the more affluent: one-fifth to one-sixth of the property value.