• Bhaskar N Subramanian

Know your Lake - a beginner's perspective

Updated: Nov 13, 2020

The first "Bellandur Kere Habba" (Bellandur Lake Festival) was held on 5th August, 2017 with primary objectives around increasing awareness amongst the community and elicit action from civic bodies. In hind sight, maybe Habba was not the right word - maybe we should have used Jagriti (awareness) or Praarambha (initiative). You'll soon know why ...

As part of this habba, I had suggested a "Know your Lake" project to be presented by kids. I collected a lot of good work that had already been done, and tried to make it simple for even kids to understand and explain. Looking back, I'm so glad that I did this because I got to know so much more in the process. Most of the content on this post is from that project. At the habba, this was presented by Vaishnavi, Reva, Sampoorna, Hrudya & Pooja, who had been briefed about it.

Let's start with Bengaluru and the Lake system we have ...

  • Bengaluru is a plateau at a height of 920 metres above sea level.

  • There are 3 primary valleys in Bengaluru as you can see from the picture to your right. Maybe this is the origin of the term Silicon Valley :-)

  • Within each valley, there are multiple lake series - interconnected lakes where water flows down from one to the other. Bellandur is within the Varthur Lake series that you can see in the picture.

Bellandur Lake is part of the Varthur Lake series within the K & C (Koramangala and Challaghatta Valley). Bellandur is the largest lake in this as well as the largest in Bengaluru. At one point it was 900 acres, but latest estimates put it at 720 acres - the rest has gone to encroachment by urban development. Arrows in the below diagram indicate the flow and you will note that water comes into Bellandur from a fairly broad area. This area, called 'Catchment Area' is 148 sq. km. for Bellandur Lake. The series ends into Varthur Lake, which flows into south Pinakini River and eventually empties into Pennar River.

There has been a lot of construction around the lake series causing disruption to the natural flow of water. For example, Agara Lake flows over into Bellandur Lake - however the land between these two now sees a lot of development. Many such constructions are approved without proper due diligence on the impact of water flows, sewage disposal, traffic capacity, etc. It is believed that the floods in K & C valley are primarily due to such uncontrolled developments. Citizen groups have protested against this, and the National Green Tribunal has stalled some projects. However, until the construction is demolished and the land is restored to its natural state allowing water flows, this stand-off will continue.

Another key observation is on the STPs (Sewage Treatment Plants). Sewage produced by Bengaluru exceeds the capacity of STPs by thousands of MLDs (Million Litres per Day). Many of the STPs may also be ineffective in the treatment. Apart from this, there is lack of ETPs (Effluent Treatment Plants) for industrial wastes from small factories. Some of the dumping may be illegal - recently citizens in the neighbourhood have reported strong pungent odour as well as itchiness to the throat and eyes arising especially around 12 am and 2 am.

Shown below is a satellite image of the lake. You will notice the dark sewage water. This picture is from 2016, but today it may be much darker. The yellow lines show the current inlets of water.

The lake has a surface area of 3.61 km2 with a maximum length and width of 3.6 km and 1.4 km. It has a capacity of 17 million cubic feet, with an average depth of 30 feet (may be lesser now due to sludge at the bottom).

Let's look into some history trivia. Bellandur lake was once the lifeline for surrounding 18 villages just a few decades ago (1970s). People used to cultivate paddy, grow vegetables like cauliflower and tomatoes in abundance and also do fishing. Over 400 fishing families were living in this neighbourhood. The lake water then was used for irrigation as well as for drinking purpose. People of Bellandur and nearby villages used to celebrate annual ‘Theppotsava’ (boat festival) on this lake. There was also a ‘sea-plane’ channel that was built into the Bellandur lake in the 1940s.

Let's conclude with the key asks as they are emerging now. A couple of years ago, experts and activists got together to create an Expert Committee Report (ECR). The ECR has outlined a very clear plan to rejuvenate the lake, and also names maps civic bodies (BDA, BBMP, LDA, BWSSB, KLCDA, etc.) that can take up specific areas. However, we have seen a lot of back and forth between these groups as well as the government's decision process. Many of the actions such as to suppress the foam with water sprays or removal of weeds seem to be very short term in nature and do not address the underlying issues. Untreated sewage continues to flow in, illegal dumping of effluents, debris, garbage etc. occur often, and possible flow of good water is blocked through unabated construction. Unless we address the root cause and the action plan from ECR end to end, we will continue to see Bellandur lake turn into a cesspool in no time.


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