Bangalore is the capital of Karnataka state, India lies between the latitudes 12°39’00’’ to 13°13’00’’N and longitude 77°22’00’’ to 77°52’00’’E. Also known as the Garden City of India and it is 3,113 feet (949 m) above sea level. Bangalore has grown spatially more  than  ten times since 1949 (~69 square kilometers to 741)  and  is  the  fifth  largest  metropolis  in  India. The rapid urbanization process in Bangalore has led to the drastic changes in land use leading to imbalance in biological and social environment. There has been a 584% growth in built-up area during the last four decades with the decline of vegetation by 66% and water bodies by 74% (Ramachandra et al., 2012). The population has increased from 5.8 Million (2001) to 8.6 Million (2011), accounting for 45.68% growth in a decade. Population density has increased from as 10732 (in 2001) to 13392 (in 2011) persons per sq. km.

Bangalore is located on a ridge with natural water courses along the three directions of the Vrishabhavaty, Koramangala-Challaghatta (K&C) and Hebbal-Nagavara valley systems, these water courses are today being used for the transport and disposal of the city’s sewage. The undulating terrain in the region facilitated the creation of a large number of tanks in the past, providing for the traditional uses of irrigation, drinking, fishing and washing. This led to Bangalore having hundreds of such water bodies through the centuries. Lakes of Bangalore are all built and interconnected by an intricate network of canals. These inter connected series of lakes help capture monsoon overflow, and store it for use in the post monsoon season, that help recharge ground water aquifers. Large scale unplanned developmental activities in recent times due to uncontrolled urbanisation in the lake catchment, has resulted in reduced catchment yield and higher evaporation losses. Inefficient primary feeder channels, encroachment of raja kaluves resulting the lake water shortage and drying. However, this shortage has been supplemented by an increased quantum of sewage inflow by local regulatory boards such as BWSSB (Bangalore Water Supply and Sewerage Board), BDA (Bangalore Development Authority) and LDA (Lake Development Authority). Due to the sustained influx of fresh sewage over a decade, nutrients in the lake are now well over safe resulting in eutrophication. There are substantial algal blooms, dissolved oxygen depletion and malodor generation, and an extensive growth of water hyacinth that covers about 70 % of the lakes in the dry season (Durga et al., 2011). The lack of awareness in appreciating the full economic benefits of water bodies led to loss of them at a greater extent.

Greater Bangalore had 207 water bodies in 1973, by 2011 left with only 93 water bodies (Figure 1) and many lakes (54%) were encroached for illegal buildings.  Field  investigation  of  all  lakes  shows  that  nearly  66%  of  lakes  are sewage fed, 14% surrounded by slums and 72% showed loss of catchment area. About 30% of the lakes were drained either for residential sectors in their ornamental borders and nearly 22% of the lakes were encroached land filling and walling of the lake margin has been observed. The major lake’s catchment area were used as dumping yards for either municipal solid waste or building debris (Ramachandra, 2009; Ramachandra, et al., 2012). Bruhat Bangalore Mahanagara Palike (BBMP) claims the city had lost the major lakes due to developmental activities such as residential layouts, playgrounds, stadiums, industries, government buildings and bus stands. Lake beds now are dominated by private projects, apartments and independent houses commercial complexes etc. The land swindlers have not left the storm water drains and lake catchment areas from encroaching and converting to commercial activities. The over exploitation of lakes and wetlands in Bangalore in recent times have resulted in rendering the ecosystem in peril by receptacles of untreated sewage, runoff from developed urban and agricultural areas, changing land use within the watershed etc. These series of unethical actions are deteriorating water quality by pollution, led to spawning of mosquitoes and became cores for dissemination of deceases. The BDA has informed the Principal Secretary to Government, Revenue Department in Apex committee meeting held on 10/05/2013 that 2311 families have illegally encroached the lake bed areas in 64 lakes in Bangalore.

There were about 43 lakes in Bangalore were utilized for various public purposes/converted into house sites or encroached by 1985. The Government of Karnataka constituted an expert committee headed by Sri N. Lakshman Rau in 1985 to examine all the aspects of the preservation restoration of lake in Bangalore. The report was accepted by the GO No.PWD 82 IMB 85 dated 11th February 1988, but implementation of the recommendations have not been implemented due to the involvement of many agencies. Ramaswamy committee, a joint Legislature committee (2007) reported an area of 747.86 ha of lake areas (2488 cases) of Government lands encroachments in Bangalore Urban district. Presently the Bangalore city is facing pathetic water supply scenario and BWSSB is not in a position to supply the required 150 litres per person water requirement to the existing population of 89 lakh people in BBMP area. Bangalore has around 1.5 lakh bore-wells to meet the water requirements. Further, well maintained lakes can augment the water supply to the Bangalore city, as there is already acute shortage of water supply. There is no way of increasing the drawl from Cauvery as the allocation by the Cauvery Water Disputes Tribunal for the entire urban and rural population in Cauvery Basin in Karnataka is only 8.75 TMC ft (one thousand million cubic – TMC ft equals 78 MLD). No more water can be drawn from Cauvery, after Stage IV, Phase II is completed by 2011.