Bengaluru’s vanishing lakes: Scientists urge society to act

By Priya Sharma, Dr. Mansee Bal Bhargava 

On April 17, 2025, a Lake Walk at Ulsoor Lake hosted by Drop Talk brought together citizens and experts to reflect on the urgent need for connecting science and society in conserving Bengaluru’s lakes. The session, part of the ongoing Lake-Pond and Water Education series by Dr. Mansee Bal Bhargava, featured Prof. T. V. Ramachandra of the Indian Institute of Science (IISc), a leading voice in ecological research and advocacy.  

Prof. Ramachandra reminded participants that “lakes are the kidneys of the city as a living organism.” Once celebrated as India’s “garden city,” Bengaluru is now often described as a “garbage city” and even a “dead city.” The decline has been gradual—“one lake, one tree, one degree at a time”—but its impact is profound: rising temperatures, falling groundwater, and vanishing ecosystems. He stressed that “science without society is incomplete,” urging scientists to step beyond laboratories and engage directly with communities.

The Economic Value of Lakes

Bengaluru’s transformation is stark: from 452 water bodies in the 1800s to just 216 today, with less than 3% green cover. Prof. Ramachandra’s Bengaluru Lake Information System quantifies the economic value of lakes using the Ecosystem Services framework—provisioning, regulating, cultural, and supporting services.  

Across Karnataka’s 39,000 lakes, the annual value of services is estimated at INR 7320.6 billion. Put simply, each hectare of lake provides services worth about INR 1 million per year. This valuation is not merely academic; it is a tool for advocacy. Citizens and policymakers, once aware of the monetary worth of lakes, are more likely to rethink pollution and encroachment.  

Concrete examples reinforce this. The rejuvenation of Sarakki Lake raised groundwater levels by 300 feet within a year and lowered local temperatures by 2–3°C, demonstrating how lakes directly improve urban resilience.

Data on Decline and Rising Health Crisis

Satellite data reveals Bengaluru’s paved surfaces have increased by 78% in 50 years, while vegetation has declined by 88% and water bodies by 79%. Of the remaining lakes, 98% are encroached. Tree cover is critically insufficient—only one tree for every seven people, when seven to eight trees per person are needed to balance carbon emissions.  

The consequences are visible in climate and health. Average annual temperatures have risen from 21°C in the 1990s to nearly 39°C today. Groundwater, once accessible at 100 feet, now lies at depths of 1,800 feet. Worse, contaminated water has triggered a health crisis: dialysis units are now common across city wards, with cases of kidney failure even among schoolchildren.  

Nature-Based Solutions and Citizen Campaigns

Experiments at Jakkur Lake in 2010 showcased the power of Nature-Based Solutions (NbS). A constructed wetland and algal park achieved 80–90% nutrient removal without electricity, eliminating nitrates from 300 wells and providing clean water to hundreds of households.  

Citizen campaigns at Varthur and Bellandur Lakes mobilized youth, leading to Supreme Court intervention and penalties against the state government. The removal of 11 million cubic meters of silt revitalized agriculture, with farmers reporting bumper crops and women earning additional income. These cases illustrate how science, when connected to society, yields tangible benefits.

Building Environmental Literacy

Environmental literacy in Bengaluru is just 3.5%. Programs like IISc’s “Know Your Ecosystem” and the Annual Lake Symposium aim to change this by engaging students and communities in hands-on experiments, biodiversity mapping, and water quality monitoring.  

Water testing labs in schools and the Bengaluru Lake Information System empower citizens with data, enabling judicial action against encroachment. Cultural and spiritual traditions also serve as powerful communication tools. Ancient texts like the Matsya Purana equate cutting a tree or covering a lake to “killing ten children,” a metaphor that resonates deeply in local contexts.

The Way Forward

The session outlined six pathways for convergence of science and society in lake conservation:  

- Economic valuation: Demonstrating lakes’ monetary worth to influence policy and public perception.  

- Open data: Making water quality and biodiversity information accessible for accountability.  

- Community engagement: Scientists stepping out of labs to communicate in local languages and forums.  

- Cultural communication: Using ecological wisdom from scriptures to connect with society.  

- Decentralized management: Rejuvenating lakes for rainwater harvesting and wastewater treatment.  

- Teachers as activists: Leveraging educators’ social responsibility to build a generation of conservation advocates.  

Ultimately, the true measure of science lies not in publications or awards but in community wellbeing—when farmers prosper, wells provide clean water, and children are spared from preventable illnesses.  

***

Acknowledgement: We acknowledge the insights of Prof. T. V. Ramachandra, Coordinator of the Energy and Wetlands Research Group at IISc.  

---

Priya Sharma is a postgraduate student from the Indian Institute of Forest Management, Bhopal.  Dr. Mansee Bal Bhargava is an entrepreneur, researcher, educator, speaker, and mentor. More about her is available at mansee.in, edc.org.in, and wforw.in