Lake rejuvenation: A restart from periphery

Faced with the prospect of an impending water catastrophe, shrinking lakes and a culture of rampant encroachments, lake rejuvenation had entered Bengaluru’s lexicon as a fashionable buzzword. But barring a few, isolated success stories, this has not dramatically altered the city’s fall into a disastrous eco-chaos.

Bellandur lake froths every now and then, competing for attention with the Varthur lake downstream. Fancy revival plans are announced, a few steps undertaken with much fanfare and photo-ops, before the spotlight shifts. Are Bengalureans forever destined to gulp down this façade of rituals or is there another, more realistic way out?

On the city’s outskirts, bordering the once sacrosanct green belt, a unique citizen-driven, corporate-sponsored, community-enforced lake revival project is now underway. In just 45 days, this initiative has completely transformed the dying Kyalasanahalli lake, breathing fresh life and dramatically rebuilding an ecosystem of plants, aquatic life and birds.

Vabasandra lake

Beyond this 36-acre water body, the Vabasandra and Gavi Kere lakes upstream are now being prepared for rejuvenation before the monsoon sets in. On Wednesday, as a DH team visited the area, the Vabasandra lake lay there completely transformed from what it was only three months before.

The canals that once fed sewage into the lake had been diverted, its inlets cleaned up and rebuilt. But it took the spirited activism of a conservationist, Anand Malligavad and over a thousand local community members to clear the lake of its silt accumulated over years of decay. The mud extracted was used to create islands, each harbouring a big tree, fruit-bearing plants and an ecosystem of its own.

Awaiting monsoon

Awaiting the monsoon rains, the Vabasandra lake is now mostly dry. But the lake activists are confident that this too will go the Kyalasanahalli way. Copious rains in 2017 had filled that restored lake with 20ft of water. Over 50,000 fish were introduced. On Thursday, the DH team spotted people fishing in that lake, once the abode of waste-dumping. Today, it has 15ft water despite rains failing last year.

But how systematic is this lake revival project? How different is the approach from the rejuvenation efforts that have only partially succeeded in the city’s urban lakes?

To understand this, Malligavad unveils a larger plan, a project that comprises 45 lakes along 11 streams, all leading up to the big Hennagara lake.

Upstream to downstream

The big idea, articulated by the conservationist, is this: Rejuvenate the lakes from upstream to downstream methodically. “By reviving a total of 900 acres of lakes this way, we could cater to a quarter of Bengaluru’s water requirement.”

Is this really a workable idea? The Lake Revivers Collective, formed by Malligavad, The Better India (TBI) and hundreds of volunteers, is convinced that this is the way to go. TBI helped raise over Rs. 8 lakh through crowdfunding to revive the Gavi Kere in the lake chain. More funds are now being raised through TBI’s Milaap page.

Of course, the same strategy cannot be adopted in highly polluted lakes such as Bellandur Lake, which receives about 40% of the city’s sewage, untreated. But the broader plan of first targeting all the lakes upstream could work.

The Collective’s plan is to first revive all the lakes that feed water into the biggest lake along that stream. But there is an elaborate process that combines upgrading water capacity of each lake, improving the feeder canals, and building a sustainable ecosystem.

Natural sustainability

The rejuvenation is not about cosmetic change. Ultimately, the Collective’s aim is to create ecological lakes with natural sustainability. “First, the lakes will be desilted. This will increase the water-holding capacity of that lake and reduce the flow of excess water to the other lakes downstream for one or two years.”

But once the revived lake is filled up, the overflowing water will continue its course. Yet, there is a method here. Explains Malligavad: “This run-off water now goes everywhere. This running water needs to be slowed down to walking water and then to sitting water which seeps down, making it easy to remove all the silt.”

Urban lake challenges

In these suburban lakes with low sewage inflow, rejuvenation will be simpler, reminds conservationists working on city lakes for decades. Most lakes within the city have huge volumes of untreated sewage flowing in unchecked. The challenges are formidable.

Friends of Lakes convenor, V Ramprasad elaborates, “We are looking at every lake in isolation and don’t consider the micro watershed region. Any rejuvenation effort should cater to the whole series of upper riparian lakes.”

Sewage inflow

Lack of an integrated approach has led to many rejuvenated lakes getting polluted through inflow of sewage. “This happened in Jakkur lake, where sewage entering from the Sampigehalli side undid all the gains achieved. In Challakere lake, one inlet of sewage destroyed the water body. Here, the sewage was mixed with the toxic industrial effluents.”

Ramprasad emphasises the need for characterisation of the sewage. “Instead of Sewage Treatment Plants (STPs), Effluent Treatment Plants then become necessary. There is also the issue of groundwater contamination.”

Diversion drains

To tackle the sewage inflow, many rejuvenation projects have taken the easy way out: Diversion drains that take the sewage to the next lake downstream. Lake experts say this is one reason why Bellandur lake has ended up getting almost half of the city’s waste water.

These loopholes in rejuvenation strategies would have to be plugged to boost the efficiency of future projects. The state government had announced a Rs 348 crore package to develop and rejuvenate 59 lakes. The Bruhath Bengaluru Mahanagara Palike (BBMP) is set to get about Rs 250 crore for lakes within the city.