Scientists, citizen activists and the Karnataka State Pollution Control Board (KSPCB) are unanimous about one bitter truth: Inflow of untreated sewage has poisoned Bellandur and Varthur lakes almost beyond redemption. But the unanimity is shattered when responsibility has to be fixed.

On Thursday, as a DH team forayed deep into Bellandur lake territory, the makeshift bund road running up to the Koramangala-Challaghatta Valley Sewage Treatment Plant (STP) offered a ringside view of the lake in all its jet black splendour.

Despite attempts to clean up parts of the lake, to desilt and clear the water hyacinths, the city’s largest water body remains buried in muck. The unbearable stench, the vast expanses of shallow, polluted water is proof of a system gone horribly wrong for years.

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Waste water, both treated and untreated, flowing from the apartment complexes into the lake is apparently only part of the problem. Even if the KSPCB manages to arrest this flow through stringent penalties, could they stem the inflow of pollutants from dozens of lakes upstream?

Will all these change over the next couple of years? Consider this: The Bangalore Development Authority (BDA) has recently floated a tender to desilt, rejuvenate and develop Bellandur lake at an estimated cost of Rs 250 crore. The Authority says the process can be completed in one year. Also on its agenda are strengthening of the tank bund, parks, walkways and other beautification.

But how realistic is the plan when almost 40% of the city’s sewage ends up in the lake? The BDA says it is in the process of draining out the sewage. Filled with sewage, the canal built along the bund road is proof enough. Yet, a question remains: How will the water be treated when the efficiency of the STPs is at its lowest?

By BDA’s own admission, the lake has about 50 lakh cubic metres of silt, while Varthur lake has about 35 lakh cubic metres. The Authority has now offered the silt for free to farmers and brick-makers.

Considering the size of the city’s largest lake, the silt could be in excess of 70,000 truckloads, notes Ramprasad from Friends of Lakes (FoL). “Shifting it away, transporting it through the already congested roads would be a logistical nightmare. If full rejuvenation of the lake is the objective, one year will not be adequate at all,” he points out. Unless the recommendations of the expert committee on lakes are followed, rejuvenation would mean only beautification, says Ramprasad. To make a real difference, the silt would have to be removed completely. Cosmetic desilting will not help. Ever since the frothing and fire in Bellandur and Varthur lakes hit global headlines, the National Greens Tribunal (NGT) has taken a tough stance, pulling up the BDA, the Bruhath Bengaluru Mahanagara Palike and KSPCB.

After decades of neglect, the Varthur lake has also been lined up for rejuvenation in two phases. BDA has called for tenders at an estimated cost of Rs 119 crore. Desilting, strengthening of the bund, wetland formation and an idol-immersion tank are all in the pipeline.