Greater Bangalore with an area of 741 square kilometres lies between the latitudes 12°39’00’’ to 13°13’00’’N and longitude 77°22’00’’ to 77°52’00’’E. Bangalore city administrative jurisdiction was widened in 2006 by merging the existing area of Bangalore City spatial limits with eight neighboring Urban Local Bodies (ULBs) and 111 Villages of Bangalore Urban District (Sudhira et al, 2007). Thus, Bangalore has grown spatially more than ten times since 1949 (69 square kilometres) and is a part of both the Bangalore urban and rural districts. Bangalore is located at an altitude of 920 metres above mean sea level, delineating three watersheds: Hebbal, Koramangala-Challaghatta and Vrishabhavathi watersheds. The undulating terrain in the region has facilitated creation of a large number of tanks. The mean annual total rainfall is about 880 mm with about 60 rainy days a year over the last ten years. The summer temperature ranges from 18 °C – 38 °C, while the winter temperature ranges from 12 °C – 25 °C. Bangalore, thus, enjoys a salubrious climate all year round.
An exploratory field survey of 105 lakes in Bangalore was conducted (figure 4a). The physico – chemical characteristics of 80 lakes were assessed which include lakes in the 3 different valleys (figure 4b):

• Hebbal Valley:Allalasandra, Bellahalli, Chelekere, Chikkabettahalli, Chikkabanavara, Chokkanahalli, Hebbal, Hesaraghatta, Jakkur, Kalkere, Kattigenahalli, Kogilu, Maragondanahalli, Mathikere, Nagavara, Narsipura 1, Narsipura 2, Palanahalli, Rachenahalli, Rampura, Sankey, Thirumenahalli 1, Thirumenahalli 2, Yelahanka and Yelemallappashetty.
• Vrishabavathi Valley:Anchepalya, Andrahalli, Baallehannu, Dasarahalli, Deepanjali Nagara, Doraikere, Dubasipalya, Hemmigepura, Herohalli, Kengeri, Komghatta, Konanakunte, Mallathhalli, Sompura, Ullal and Uttarahalli.
• Koramangala-Challaghatta Valley (KC):Agara, Ambalipura, Arekere, Bagmane, Bhattrahalli, Begur, Bellandur, Bommasndra, Chikkabegur, Chikka Togur, Chinnappanahalli, Chunchugatta, Doddanekundi, Hebbagodi, Hulimavu, Kaikondrahalli, Kammasandra 1, Kammasandra 2, Kasavanahalli, Kelagiankare, Kothanur, K R Puram, Kundalahalli, Lalbagh, Madivala, Mahadevapura, Munnekolala, Mylasandra 1, Mylasandra 2, Nallurahalli, Rayasandra, Sheelavanthakere, Singasandra, Subbrayanna, Ulsoor, Varthur, Vittasandra, Yediyur and Yeklgata.

In the exploratory survey, it was found that about 25 lakes were fully covered with macrophytes or dumped with solid and liquid wastes. Some were under restoration activities. Lake such as Lakasandra had completely turned to a barren land due to the dumping of building debris. Those 25 lakes are (figure 6a) are:

• Hebbal Valley: Amrutahalli, Doddabommasandra, Kammgondahalli, Puttanahalli, Horamavu, and Horamavu Agara.
• Vrishabavathi Valley:Avalahalli, Doddabidirakallu, Goudanakere, Herohalli, Hosakerehalli, Kempambudhi, Nalagadderanahalli, Nayandanahalli, Shivapura and Vaddarapalya.
• Koramangala-Challaghatta Valley (KC):Benniganahalli, Byrasandra, Chandapura, Gottigere, Garvebhavipalya, Lakasandra, Sarakki, Seetharamapalya and Veerasandra.

Figure 4a:Lakes monitored (105 lakes) at different time periods during the survey.

Figure 4b:Lakes (80 lakes with water quality) monitored during different time periods