Reviving Sembakkam Lake: A battle against sewage, encroachments and government neglect

Once a vibrant water body, Sembakkam Lake is now a shadow of its original self. Residents push for restoration before it's too late.

As the first light of dawn paints the sky in hues of orange and gold, 17-year-old Ravi steps out of his home. The cool breeze brushes his face as he walks towards the expansive, 150-acre Sembakkam Lake for his morning bath. Millipedes and blanket worms scuttle across the road, their movements as steady as a train on its tracks. A flock of white pelicans glides across the sky as he nears the lake, where a few people fish in the serene waters. After his bath, Ravi returns home to prepare for college.

This was M Ravi’s experience as a young man in 1974 when Sembakkam Lake was still a thriving part of his community. Now 62, Ravi recalls those mornings with nostalgia. Today, the lake has shrunk to 104 acres, and a stagnant pool of black water remains. As Secretary of the Sri Sarvamangala Nagar Residents Association, Ravi has been at the forefront of efforts to restore Sembakkam Lake for the past 25 years.

In Part 2 of the series on the pollution of water bodies, we examine Sembakkam Lake’s deterioration and the challenges residents and environmentalists face in their fight for its conservation.

The decline of Sembakkam Lake

As Ravi explains, agricultural land once surrounded Sembakkam Lake. Over time, much of this land was converted into residential plots. However, the government failed to provide essential infrastructure, such as an underground drainage system, to manage the growing urban sprawl. As a result, raw sewage from surrounding buildings has been flowing directly into the lake and nearby water bodies, worsening the environmental crisis. Decades later here we are trying to find the missing links in dire straits.


Read more: Saving the eri: How communities came together to restore Chennai’s lakes 


The water flow and natural connections

Sembakkam Lake was once part of a larger water network. Water from the Pachamalai Hills flowed into Chitlapakkam Lake, which in turn fed into Sembakkam Lake. Ravi recalls, “Pachamalai channel used to have hip-level water. To reach the Hasthinapuram bus stop, we would cross the 30-foot-wide Pachamalai channel in the 1970s.” Currently, the channel is almost unrecognisable, and the natural water connections have been severed due to rampant urbanisation.

Pachamamalai channel
The sorry state of Pachamalai Channel in Vinobaji Nagar 11th street. Pic: Shobana Radhakrishnan
Chitlapakkam Kalangal
Chitlapakkam Kalangal (Kalangal is part of the lake from which the surplus water overflows into the next downstream channel.) Since this natural system is disconnected due to urbanisation, the WRD has built a cut-and-cover drain connecting Chitlapakkam Lake with Sembakkam Lake. Pic: Shobana Radhakrishnan

The impact of urbanisation

Meanwhile, in a significant change, surplus water from nearby Selaiyur Lake is now flowing entirely into Sembakkam due to encroachments and altered natural pathways.

Darwin Annadurai, an environmental scientist at Eco Society India explains, “A portion of surplus water from Selaiyur Lake once flowed towards Chitlapakkam Thangal (Chitlapakkam Thangal is a separate water body, which was situated at a lower elevation from the lake). But now the Chitlapakkam Thangal and the channels connecting Selaiyur Lake to Thiruvanchery Lake and Rajakilpakkam Lake have disappeared because of encroachments and all the water flows towards Sembakkam.”

This disruption in natural water flow exacerbates the sewage issue. The inflow of untreated sewage from both residential and commercial buildings — into lakes like Chitlapakkam and Selaiyur— has made these water bodies a dumping ground for raw sewage.

Selaiyur lake
Raw sewage from the houses around Selaiyur Lake getting directly discharged into the lake. Pic: Shobana Radhakrishnan

To address this issue, Chitlapakkam residents have come up with a solution to divert the sewage water entering the lake.

Chitlapakkam’s 4Ds model

The 4D model of Chitlapakkam involves deflecting, draining, desilting and deepening. “All the inlets to the Chitlapakkam Lake have sewage gates from where the polluted water is deflected through the sewage interceptor drains and taken to sewage collection wells. From the collection wells, it is taken to a conventional Sewage Treatment Plant (STP) through pumping arrangements. During non-monsoon, sewage is not allowed into the Chitlapakkam Lake,” explains Dayanand Krishnan, a GIS expert and member of Chitlapakkam Rising. All this can be done within Rs 10 crore and can help in storing rainwater in the lakes and mitigating floods, he adds.

Chitlapakkam to Sembakkam cut-and-cover drain
Ravi points out that a cut-and-cover drain might connect the Chitlapakkam Lake with Sembakkam Lake but it does not solve the fundamental issue of sewage water mixing in the lake. However, the WRD official says that the purpose of cut-and-cover drains is to mitigate floods. Sewage inflow has to be addressed by the local bodies. Pic: Shobana Radhakrishnan

“As of now, we are diverting the sewage water from Chitlapakkam Lake to Sembakkam Lake. The collection well construction is close to completion and pumping arrangements have been made to pump the sewage from Chitlapakkam Lake into the STP. It should be operational in a few weeks,” says a WRD official.

dysfunctional STP
A dysfunctional STP near the cut-and-cover drain where water from Chitlapakkam Lake enters Sembakkam Lake. Ravi points out that the government could have upgraded this STP according to the increasing population. However, the lack of maintenance did not give scope for it. Pic: Shobana Radhakrishnan

As a result, Sembakkam Lake receives sewage water not only from Chitlapakkam Lake but also from Selaiyur Lake (which carries polluted water from Irumbuliyur Lake) and the buildings in Sembakkam. “This leads to flooding in Sembakkam and the surrounding areas during the monsoons,” says Ravi.

So, the two missing links in the entire system are Sembakkam to Nanmangalam (90% completed) and Nanmangalam to Keelkattalai. “We could prevent flooding once this work is over,” says the WRD official.


Read more: Lessons from the past must guide the restoration of Chennai’s lakes


Encroachments and government neglect

However, it is not just flooding and sewage. Over the years, both government and private entities have encroached upon the lake. “First came a Pillaiyar temple and then a political flag post, marking the first encroachments in Sembakkam Lake,” recalls Ravi.

A dump site
A garbage management facility along with a crematorium run by Pallavaram Municipality on Sembakkam Lake. Pic: Shobana Radhakrishnan
Garbage dump on Sembakkam Lake
Garbage dumped on the encroached part of Sembakkam Lake. Pic: Shobana Radhakrishnan
Government laid road on Sembakkam Lake
The government-laid road on Sembakkam Lake. Pic: Shobana Radhakrishnan
A private school and an apartment complex built on Sembakkam Lake
A private school and an apartment complex built on Sembakkam Lake. Pic: Shobana Radhakrishnan
Sembakkam Lake
“Nowhere in the city could you find such a huge space between the lake’s catchment area and the road. We were able to retain this only after long legal battles,” says Ravi. Pic: Shobana Radhakrishnan

Owing to the relentless efforts of Ravi and Sri Sarvamangala Nagar Residents Association, and the legal battles they took up, Sembakkam Lake still has 104 acres. Other lakes nearby have lost more than half of their catchment areas to encroachments.

Sembakkam Lake needs restoration, not lakefront development

Sembakkam lake
Non-native trees planted around the Sembakkam Lake during the previously done developmental work. Ravi insists that planting Palm trees will strengthen the bunds but the non-native trees are only ornamental. Pic: Shobana Radhakrishnan

Meanwhile, CMDA has allocated Rs 10 crore for the lakefront development of Sembakkam Lake. “We do not want any amphitheatres, parks or concrete pathways along the lake bunds. We want a clean lake in which rainwater can come naturally and flow to the next downstream lake without flooding the area,” says Ravi.

The WRD official says that the detailed project report (DPR) will also include sewage deflection and the setting up of peripheral drains along with the usual lakefront development works. The Chitlapakkam model does not hold good for Sembakkam Lake, as Chitlapakkam has point flooding and a much lesser catchment area. On the other hand, Sembakkam sees flash flooding and has a larger catchment area. “We will make slight modifications to the Chitlapakkam model to address this,” adds the WRD official.

Many issues get entangled in jurisdictional conflicts between different government departments, and Sembakkam Lake restoration is no exception. The WRD along with Tambaram and Pallavaram Municipal Corporations need to take proactive measures to stop the sewage inflow in the lake.

What residents want

  • Stop sewage inflow into the Sembakkam Lake and bring the UGD connections expeditiously
  • Implement Tamil Nadu Protection of Tanks and Eviction of Encroachment Act, 2007 to remove encroachments
  • Measure the lake and demarcate the boundaries

As I spoke with Ravi, I realised that the vibrant lake ecosystem he once knew may never be experienced by my generation. The question remains: What will be left of this lake if we don’t act now?

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Comments:

  1. Greetings
    we need to turn the problem as a boon
    For years sewage has got accumulations in Lake.
    All these soil are nutrient rich, need to be transfered to Neserby agri farms.
    When this transfer is done, the lake land wellbeing porous, vibrant ready to be nature centric.
    Allbgood RW need to be harvested in Lake or in dugwells around Sembakkam Lake.
    Our Best wishes for a Great future for Sembakkam and Selaiyur and others.
    … wll wshs for gr8 prospects..
    filed by Prof Ajit Seshadri, Chennai

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