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Sunday, January 23, 2022

Lakes of Bengaluru: Rachenahalli lake, a lifeline choked by rampant development

Spread across 104 acres, the lake in Thanisandra supported agricultural activities and livestock till 2000. Today, large-scale construction has disrupted the natural flow of rainwater, as a result of which it overflows during heavy spells of rain.

Written by Aksheev Thakur | Bengaluru |
Updated: November 29, 2021 6:59:27 am
In the past few years, several residential premises and academic institutions have come up on the lake bed while the civic agencies looked on as mute spectators.

On November 21, the Yelahanka zone in north Bengaluru received 153 mm of rainfall which caused three key north Bengaluru lakes to overflow – the Yelahanka lake, the Jakkur lake and the Rachenahalli lake. The immediate effect was the inundation of residential properties and roads.

The flooding triggered by the short, but heavy, spell of rain has been attributed to the large-scale construction activity in the Hebbal valley region which has disrupted the natural flow of rain water from lakes in the upper regions of north Bengaluru, like Yelahanka lake, to lakes in the lower regions, including Rachenahalli lake. Experts have identified constructions that have come up on the lake beds over the years as the single major cause behind the flooding of north Bengaluru after the downpour of November 21.

Lake water being pumped out

Rachenahalli lake (Thanisandra, Bangalore North)

Spread across approximately 104 acres, the Rachenahalli lake is located in Thanisandra, north of Bengaluru, within the Yellamallappa Chetty lake series in the Hebbal valley. The Jakkur lake and the Sampigehalli lake are some of the lakes upstream to Rachenahalli lake, while the Nagavara and Kalkere are downstream.

In the past few years, several residential premises and academic institutions have come up on the lake bed while the civic agencies looked on as mute spectators. In violation of the National Green Tribunal (NGT) order on maintaining a 75-metre buffer zone around the lake, some of these new buildings have come up within 30 metres of the lake. The inlets going into the lake carry a mixture of sewage and stormwater.

A 2003 study on ‘Economic valuation of wetlands’, conducted by Dr TV Ramachandra, R Rajinikanth and VG Rajini of the Indian Institute of Science (IISc), reveals that the tank had heavily supported agricultural activities and helped in the maintenance of livestock in the surrounding villages till the year 2000.

Panaromic view of Rachenahalli lake

During his tenure as executive director of Mahatma Gandhi Institute of Rural Energy and Development (MGIRED), former Indian Forest Service officer Punati Sridhar involved locals as part of efforts to safeguard the lake. “In 2015, it was not even a place where people could walk around. I involved local citizens who showed interest in restoring the sanctity of the lake. Construction labourers who lived close by in huts used to defecate near the lake, so I asked the contractors to provide them with toilet facilities. Along with local citizens, I used to do weekly cleaning of the lake by removing trash. We requested the BBMP to provide watchmen,” he said.

Inspired by the civic action of the non-profit Jalaposhan, Dr Shobha Ananda Reddy who was working as the additional director of MGIRED, took up efforts towards reviving Rachenahalli lake in 2015 and worked closely with Sridhar. With the support of MGIRED staff and students, cleaning of the bund area was taken up. A volunteer citizen group of eight active members was formed for managing the lake, which started to work with the Bangalore Development Authority (BDA), Bruhat Bengaluru Mahanagara Palike (BBMP) and local MLA Krishna Byre Gowda. Jalmitra, an NGO, was founded with seven trustees that year with a mission to restore the lake. In 2016, the lake’s custody was transferred from the Bangalore Development Authority to the Bruhat Bengaluru Mahanagara Palike (BBMP).

Lake conservationists point out that permissions granted by the civic authorities for constructions on the lake bed was among the reasons that led to the flooding of residential premises and academic institutions, like the premier Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), during the recent rains.

The inlets going into the lake carry a mixture of sewage and stormwater.

In 2003, ignoring protests by the Lake Development Authority (LDA), the Revenue Department allotted 18.39 acres of Rachenahalli Lake to JNCASR. The MGIRED was allotted 9.88 acres (four hectares). On its part, the BDA too encroached 18 acres of land around the lake by building residential complexes and part of the land was also taken over by a private builder.

According to Dr Reddy, the chief issues plaguing the water body are incomplete underground drainage, blocked manholes and reduced width of the stormwater drains (SWD) that bring water to it. “The SWD is not desilted regularly and parts of the SWD downstream of Rachenahalli lake have been encroached. The approach to rejuvenation of lakes must change. The focus should be on reviving the upstream lakes first and then gradually covering all lakes in the valley. Unfortunately, due to various factors, the government takes up individual lake projects which later get affected by the pollution upstream and excess water flow,” she said.

A senior official in the Bengaluru Water Supply and Sewerage Board told The Indian Express that a 10 MLD sewage treatment plant (STP) has been proposed for Rachenahalli lake. “Funds have been allocated for setting up the STP. Work is under progress,” he said.

Chief issues plaguing Rachenahalli lake

  • Incomplete underground drainage network
  • Stormwater drains (SWD) not desilted regularly
  • Blocked manholes
  • Reduced width of SWDs
  • Encroachments on parts of the SWD downstream of Rachenahalli lake
  • Sewage treatment plant yet to be installed

Lakes upstream: Jakkur lake, Sampigehalli lake

Lakes downstream: Nagavara, Kalkere

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