Bengaluru: Bengaluru, the tech hub of Karnataka also known as the 'Garden City' of India, is dotted with numerous lakes. But booming infrastructure over the last 25 years has resulted in elimination of many waterways with others choked by a mix of domestic and industrial waste.
Chief Minister B.S. Yediyurappa kicked off an ambitious plan Mission 2022 last week which focuses on four major areas and one of them is Hasiru Bengaluru (Green Bengaluru). In order to accomplish this, the city's civic body - Bruhat Bengaluru Mahanagara Palike - has been roped in to improve about 25 lakes in the city.
The BBMP is pooling in resources worth around Rs 100 crore of which 50 per cent will be secured from Chief Minister's Nagarotthana grants.
Both Karnataka High Court and National Green Tribunal (NGT) on several occasions in the past have come down heavily on the Karnataka government's ineptitude in tackling lake pollution and razing down encroachments.
After NGT's intervention, the Karnataka State Pollution Control Board, has also revised standards limiting phosphate content.
"All manufactures located in Karnataka are hereby informed and directed to adhere to the standards with immediate effect. Similarly, detergent powders, detergent bars and synthetic detergents manufactured outside Karnataka are also required to adhere to the above specifications while being marketed in the state," the recent notice by the pollution control board said.
According to the KSPCB, as per the NGT directions, the BIS has limited the phosphate content in household laundry detergent powders, detergent bars and synthetic detergents for washing woollen and silk fabrics as the presence of phosphorus in excess in water bodies is known to cause "eutrophication" (loosely defined as accumulation of nutrients), leading to algal growth. This poses a risk to aquatic life.
Bengaluru Civic Commissioner, N. Manjunath Prasad had stated that the BBMP had cleared about 60 per cent of encroachments on lakes and in a couple of months, the BBMP will achieve 100 per cent results.
Till 1960, there were 280 lakes in the city and in 2020 the number stands at 205 and of this not a single lake has water fit for drinking or bathing.
'Wetlands: Treasures of Bangalore (Abused, Polluted, Encroached and Vanishing)', a study headed by IISc's Professor T.V. Ramachandra shows the current scenario of Bengaluru's lakes.
IISc surveyed 105 lakes in the city and found that only four lakes are in good condition. 90 per cent of the lakes are polluted with sewage. Of these, 25 were covered by water hyacinth - an indicator of the sewage flow - throughout the year. The lakes are also covered with solid and liquid waste with very little water. The study also found that the water in the lakes was not fit for consumption.
The study revealed that only Mylasandra lake has water fit for consumption. Almost 98 per cent of the lakes were encroached by land mafia. Another finding shows just 29 per cent of the lakes were suitable for breeding fish. They also found that the lakes in Koramangala-Challaghatta valley were more polluted than the lakes in Hebbal valley.
Most lakes in Bengaluru are artificial (also known as tanks), built and maintained under the patronage of rulers over many centuries. The Hoysalas, Wodeyars, Kempegowda and Tipu Sultan, were all patrons of lakes. They all built more than 1,000 lakes and tanks in the city which are now slowly fading out from the heart of the city due to rapid urbanisation and discharge of effluents in the water bodies.
Bengaluru city's lakes are all rain-fed receiving rain and other surface water from the catchment, the area of land within from which all surface water drains and converges. Bangalore's lakes are interconnected by a network of storm water drains or 'kaluves', which carry excess water from lakes in higher elevations to those in lower elevations. This cascade system ensures both flood control and water conservation.
Lakes in Bangalore receive water from storm drains that flows through inlets. They also receive a good amount of sewage from leaky pipes and the streets. Excess water is drained out by outflow weirs or culverts, known as 'kodis'.
Man-made lakes have 'Bunds' or ridges built to hold the water back and create a reservoir. Lakes also have a command area or 'achcut', land downstream that was irrigated by the lake in older times.