Bangalore in earlier days was very well known as "The City of Lakes". Kempegowda, the founder of Bangalore, who had broad vision, established several tanks and lakes to impound runoff water, so that the same could be utilized for better purposes and also enhanced the beauty of our garden city. The farsighted founder dotted the city with numerous lakes/tanks in and around the city to ensure, that its citizens would always have abundance of water to drink, irrigate their lands and use for secondary purposes.The earliest instance of construction of tank in Bangalore dates back to the latter part of the 16th century, when the founder of Bangalore, Kempegowda built the Ulsoor tank covering an area of 125 acres. The first instance of contamination of Ulsoor tank by sewage was reported way back in 1883 after which the use of lake water for purposes of public consumption was prohibited. Records show that till 1960 there were 262 water bodies in Bangalore. Today the figures have declined to about 81 of which 34 are recognized as live lakes. These figures denote a reduction of water bodies as high as 35%, while in terms of water spread area it shows a decrease of 8.6%.
In the urban area of Bangalore, water bodies cover about 5% of the land. The lakes of Bangalore have attained an important ecological status as the lakes have turned into lentic-closed aquatic habitats. These lakes form a unique irreplaceable system. The manmade lakes of this zone can be viewed as a basin with several zones of water at varying depths, abutting a deeper zone that lies towards the bund. The zonation is dynamic and promotes the growth of variety of emergent, floating, anchored floating and submerged vegetation, each of which shows a preference for a particular range of water depths.The lakes of Bangalore are home to a diversity of living beings. The different types of biodiversity found in lakes of Bangalore are:
The lakes in Bangalore, which are scattered and placed in all vantage areas, have an important role in recharge of groundwater. The capability of these lakes to trap and store rainwater is enormous. The rainwater that could be harvested through these lakes would meet the city's water requirements partially. A large number of lakes in and around Bangalore had a vital hydrological role in recharging groundwater in its lower command areas and also in the valley portions enriching the flora and fauna and giving a green belt around every lake. But, with the decrease in number of lakes year by year, the recharge of groundwater has steadily declined to a very great extent.The terrain of Bangalore is such that the water flows out on sloping land, but does not infiltrate quickly into the surface soil horizon. This phenomenon of water repellency is due to crusting of surface soils devoid of vegetation. If this runoff water is not trapped and groundwater aquifers not recharged, the scenario would indeed become bleak.Lakes as recreational areas: Lakes are vital parts of freshwater ecosystems of any country. A freshwater lake when maintained free from pollution can offer many beneficial uses in an urban area. Lakes give very beautiful landscape view to the city. Lakes encircled with trees and parks perhaps could be the only place where the urban population can find a place close to nature and provide aesthetic enjoyment and recreational potential. The urban population can free themselves from the polluted urban air and find solace in the cool air by the lake side and relax in recreational activities such as swimming, boating, fishing and strolling along the lake shores.
The city of Bangalore does not have any perennial river. It is dependent on the Cauvery river, about 140 km away for water. The naturally undulating terrain of Bangalore city, with its hills and valleys, lends itself perfectly to the development of lakes that can capture and store rainwater.The lakes in Bangalore form a chain of hydrological connection through them. The flow of water runs from North to South-East as well as South-West along the natural gradient of the land. During monsoons, the surplus water from the upstream lake flows down into the next lake in the chain and from there further down. This connectivity did not allow an overflow of water out of the lake into the surrounding area as additional quantity of seasonal water was transferred to other lakes.The lakes thus forms a chain of reservoirs in each of the three valley systems. Each valley at the ridge top gives birth to small streams. These cascades down to form major stream systems in three valleys namely Hebbal Valley,Koramangala & Challaghatta Valley and Vrishabhavati Valley. These valleys are the repository of all the lakes in Bangalore and these lakes themselves are interlinked to each other through a series of chains of lakes giving a cascading effect to the whole system.