Hesaraghatta Lake, once a water source for Bengaluru, is now ravaged

The effects of sand mining: Vertical walls could collapse into the lake during heavy rains, reducing its water-holding capacity. 

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Hesaraghatta lake, whose water once nurtured half of Bengaluru, is facing threats from illegal sand mining even as vehicular movement and weekend drinks parties are driving its rich ecology to the edge.

Farmers have long used the silt from the lakebed for agricultural purposes. It is, however, the rampant mining for supplying raw material to brick kilns that has threatened the lake. The digging has led to the formation of about 10-foot-tall vertical walls at various places along the shoreline, which will collapse and run into the lake during the heavy rain.

Ornithologist M B Krishna said that except for the scientific removal of silt, any digging in the area would affect the ecology of the lake. "As the runoff water carries mud, the water collected in the lake turns turbid and blocks the penetration of light, affecting aquatic ecology. Similar is the effect of unmonitored movement of vehicles, which will ruin the grass cover that prevents the topsoil from running into the lake," he explained.

Empty liquor bottles are strewn across the grassland whose unique ecosystem has made the Forest Department propose it as a conservation reserve.

Environmentalist Mahesh Bhat, who has been fighting for the lake for a decade now, said increased human activity in Hesaraghatta threatened the natural ecology. "People coming for parties and those doing stunts on vehicles are a big nuisance. The department needs to monitor the entry of people," he said.

Besides dire warnings from experts about the death of the waterbody and the disappearance of the grassland, government agencies, including Isro and EMPRI, have noted the problems. "Extensive soil excavation and dumping of the waste are happening due to lack of management and maintenance. Even though the Hesaraghatta reservoir is free from the sewage influx, the water is not used for any purpose," a 2015 study by EMPRI noted.

Activist Joseph Hover said the governance of the 500-acre lake area and the accompanying grassland needed improvement. "The Forest Department has already proposed to conserve it. The BWSSB, the animal husbandry and forest departments should sit together to chart out the best measures to preserve the area," he said.

To a question on the recent fencing work failing to stop the illegal activities in the area, BWSSB Chief Engineer Ramesh said he would look into the issue. "We will deploy security guards round the clock to protect the lake," he added.