I grew up in Jayanagar, not far from Yediyur tank. About 12-13 years ago, we moved elsewhere in Jayanagar, and I didn't revisit Yediyur tank until recently. However, just a few weeks ago (on my last visit to India) we drove past the lake, and I was horrified by what I saw. Instead of a beautiful and living lake, there stood a cess pool of stagnant and foul smelling water, with a swarm of mosquitos hovering over the lake.
As a teenager, I had spent many evenings walking with our dog (Linda) on the paths in the park by the lake. The lake then was an amateur ornithologist's paradise. There were egrets, coots, brahminny kites, common kingfishers, the occational cormorant and the rarer herons. I was actually able to put my Salim Ali's handbook of Indian birds to good use here! Over the years, I've learnt more about Bangalore's avian life (which now seems to exclusively comprise of crows, pariah kites, sparrows and pigeons). Apparently, some years ago, even endangered birds such as the Great Indian bustard and the Lesser Florican were found here. Even in my school days I was astounded that city "planners" had thought it fit to reclaim tanks that ancient rulers (like the Kempegowdas, Marathas, Wodeyars, Tipu Sultan and the British) had painstakingly planned. The present Majestic bus terminus, the Kanteerava stadium and many other such well known venues were once famous tanks.
Even twelve years ago there was a channel on the other side of Yediyur tank, which let in sewage water from the houses on that side. But (apparently) the lake had sufficient inlets of fresh water/ rainwater to keep it alive. However, the construction boom of the past decade and the creation of unplanned sewage outlets (leading into tanks) have destroyed this and other lakes in the city. In the guise of "development" many beautiful tanks have been reclaimed for apartment complexes. Those that survive have all their water inlet channels clogged (and so cannot be replenished by rainwater), and also serve as dumping grounds for untreated sewage and effluents. Even tanks in the far outskirts of Bangalore (such as the tank at Hulimavu village, off Bannerghatta road, which is now being surrounded by rapidly expanding residential suburbs) are under extreme threat. Apart from destroying biodiversity and becoming a breeding ground for mosquitoes, not surprisingly the water tables in Bangalore have reached alarming levels. It is common to see people dig borewells over 400 feet deep in search of water.
But the lakes can be saved. Preventing untreated sewage discharge in to the lakes is an obvious first step, along with restoring rainwater inlets into the lakes. What is missing is a strong political will, but if the residents of this "showpiece city" demand it, the rulers cannot sit still. Awareness must start at the school and college level, and instead of engineering students (I was one of them once) wasting their time on theoretical or impractical projects, they could involve themselves in monitoring pollution levels in lakes, or designing simple, low cost treatment plants. It will be a tragic loss if the condition of Bangalore's wetlands does not improve. Bangalore will have lost its soul.