Unheeded warning, unchecked sewage flow behind Ulsoor’s lakes untimely death?

The efforts of rejuvenating the Ulsoor Lake have over the years only been able to reduce the entry of pollutants by 75 to 80 per cent.

Written by Johnson T A | Bengaluru | Updated: March 7, 2016 7:54 pm
Municipal workers clear dead fish from the Ulsoor Lake in Bengaluru, India, March 7, 2016. The reason for the death of thousands of fish remains unclear. REUTERS/Abhishek Chinnappa TPX IMAGES OF THE DAY Municipal workers clear dead fish from the Ulsoor Lake in Bengaluru, India, March 7, 2016. (Source: Reuters)

Barely three years after it was rejuvenated, Bengaluru’s Ulsoor Lake has shown signs of dying again. Dead fish washed ashore this weekend making clear the presence of more pollutants than fresh water discharged into the lake again from around eastern parts of the city.

Built in the 17th century as a source of drinking water and irrigation, the Ulsoor lake was a major source of drinking water during the British era when a military cantonment was located against its backdrop. The Indian Army’s Madras Engineering Group continues to have a unit on the shores of the lake. The lake was also the site of an annual regatta organized by the Sappers for many years.

Over the years, the lake was also a pristine picnic spot, where families descended on weekends to enjoy lush green surroundings and boating.

However, over the last three decades or so it has been frequently choked out of oxygen supply by the sewage inflow into the lake especially in the dry months. Once a city with nearly 262 lakes around it, Bengaluru currently has barely 70 lakes that are still alive.

“The lakes in Bengaluru are disappearing fast and the ones that are remaining are also on the verge of extinction. Ulsoor Lake was monitored for various physico-chemical parameters during 1996-1997. The results indicate that the lake is highly eutrophic with low dissolved oxgygen values and high nitrate, phosphate and heavy metal concentrations,” a 1997 study on Ulsoor Lake had revealed.

Multiple attempts at resuscitation of the 123 acre lake, located in the heart of Bengaluru invariably had only temporary success, with sewage flow surpassing fresh water flow into the lake from three storm water drains that empty into the lake.

Previously, the lake died at the turn of the 21st century when water hyacinth thriving on the sewage inflow choked the lake, leaving it a green leafy mass rather than a shimmering, clear water body. The incident resulted in a Rs 10 crore project in 2002 by the city corporation to revive the lake by desilting it and blocking entry of sewage into it.

However, by 2011-12 the lake was once again ailing with steadily increasing sewage flow as city’s population started to boom. In 2013, another rejuvenation was carried out where an effort was made to make the lake more people friendly – with the creation of walking tracks and clearly designated zones for activities like immersion of Ganesha statues.

The efforts of rejuvenating the Ulsoor Lake have over the years only been able to reduce the entry of pollutants by 75 to 80 per cent. In the dry season with sewage being the primary inflow into the lake, through the storm water drains in the city, the lake becomes more vulnerable. A water purifying system to clean the water that enters the lake has also not been effective.

A million warnings to authorities by environmentalists to ensure that only storm water enters the lake have gone unheeded and a familiar story of pollution is playing out again at the Ulsoor Lake.

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