Lake Health Index reveals pollution concerns in Bengaluru’s water bodies

The citizen-driven Lake Health Index project assessed the condition of three lakes in the city: Ulsoor, Doddabommasandra and Shivapura.

Bengaluru grapples with a persistent water stress, worsened by the decline in rainfall, overexploitation of groundwater and decreasing Cauvery River levels.

The water crisis has led experts and the government to reconsider using lakes as a source of water, either by storing treated wastewater or harvested rainwater. The draining of lakes, like Bellandur and Varthur, for desilting has contributed to a major part of the groundwater crisis in Bengaluru.

However, with the upcoming monsoon predicted to be normal, there is a looming concern regarding the lakes in the city. The anticipated rains may bring one of the highest influxes of pollutants, posing long-term risks to lakes’ health and the well-being of citizens who depend on them for livelihood and recreational activities. As the lakes receive runoff from urban areas, the pollutants accumulated during the dry spell could be washed into the water bodies, potentially causing ecological imbalances and health hazards.

Lakes and tanks dotting the landscape of Greater Bengaluru and the Bengaluru Urban District are historically significant. These reservoirs were built over centuries by many emperors and dynasties. Initially, they served primarily as irrigation tanks or water supply reservoirs, with secondary use such as bathing and washing. However, as urbanisation spread over agricultural fields, the need for these tanks for irrigation decreased, it has transformed the role of lakes from utilitarian to recreational and cultural hubs.

A volunteer collects a water sample from a lake
A volunteer collects a sample. Pic: Meena from India Cares Foundation

Rationale behind Lake Health Index (LHI)

Bengaluru’s lakes face significant challenges like water contamination, dwindling water levels, and urban flooding. Despite substantial investments from both public and private sectors, progress in addressing these issues has been slow. The stagnation isn’t due to a lack of effort but rather stems from disagreements among stakeholders, driven by differing values and interpretations of data. Conservationists value lakes for their diverse ecosystems, while communities appreciate them for their role in groundwater recharge and cultural traditions.

Hari Prasad explains the lake health index methodology
Hari Prasad explains the methodology. Pic: Meena from India Cares Foundation

However, the inflow of urban pollutants has altered the natural integrity of these lakes, turning them into reservoirs contaminated by sewage and industrial waste. 

Monitoring lakes is crucial for effective nutrient management, identifying pollution sources, and guiding restoration efforts. It helps assess water quality, detect changes in ecological conditions, and inform conservation strategies.

Regular monitoring enables early intervention to prevent eutrophication, habitat degradation, and loss of biodiversity, ensuring the long-term health and sustainability of freshwater ecosystems. Due to resource constraints at agencies like the Pollution Control Board’s (PCB’s), citizen engagement becomes pivotal, especially considering the varied geographic locations and seasonal changes in lake conditions.

The Lake Health Index (LHI) project was initiated to develop a lake/water body monitoring tool for assessing the ecological condition of lakes by the stakeholders and residents who regularly use the lakes. It involves evaluating diverse biological, chemical, and physical aspects to understand overall lake health, including water quality, biodiversity, and habitat conditions.

Students performing water analysis
Students performing water analysis. Pic: Hari Prasad HK

Armed with comprehensive insights into the health status of the lakes, citizens can advocate for policy changes and management interventions to address specific pollution sources and ecological imbalances.

Piloting the project

  • The project pilot testing was launched across three unique lakes, based on the land use surrounding them: Ulsoor, Doddabommasandra, and Shivapura Lake
  • The data was collected both before the monsoon season during march-April of 2021 and after the monsoon during December-January of 2021-22. In line with the citizen science framework, this initiative engaged student volunteers from several academic institutions like Ramaiah College of Arts Science and commerce, Kristu Jayanthi College to name a few, averaging 60 to 120 participants  from different educational backgrounds per seasonal cycle
  • We collected data using a tool called Open Data Kit (ODK) Collect, with subsequent data analysis conducted by Friends Of Lakes-FOL members Kaushik Dutta and Hari Prasad HK; Shashank Palur from WELL labs contributed to hydrological insights and survey construction, with Sumita Battacharyya from Ashoka Trust for Research in Ecology and the Environment (ATREE) validating the instruments
  • Funding by Bengaluru Sustainability Forum (BSF) ensured interdisciplinary collaboration for scientific data analysis. This collaboration ensured a methodical approach to data collection and analysis, fortifying the project’s scientific underpinnings. Nitrate, phosphate, and turbidity levels were assessed using Foundation for Environmental Monitoring (FFEM) testing kits, while pH, temperature, and Total Dissolved Solids (TDS) were measured with Henna pen-type sensors which are handheld devices used for measuring parameters like pH, temperature, and TDS in water bodies
  • Volunteers were divided into small groups and assigned various sections of the lake to cover. They meticulously gathered data on Sunday mornings

Summary of the pilot study

Bengaluru’s lakes reveal diverse challenges and conditions impacting their health and ecosystem. The analysis indicates that after the monsoons, pollution levels increase in Bengaluru’s lakes. 

  • Ulsoor Lake, located within residential areas, saw nitrate levels spike by 20%, from 4 mg/L to 5 mg/L. 
  • Doddabommasandra Lake, surrounded by residential and commercial spaces, saw phosphate levels rise by 15% to 7 mg/L
  • Meanwhile, industrial surroundings led Shivapura Lake’s total dissolved solids level to jump 30%, from 1500 mg/L to 1950 mg/L
  • Trash, dead fish underscore maintenance and water quality issues, especially at Shivapura Lake, where recurring fish deaths highlight issues like low dissolved oxygen and high dissolved solids. The varying pH levels from 6.5 to 8.5 in Bengaluru’s lakes indicate different levels of acidity and alkalinity based on their geographic locations 
  • High turbidity values exceeding 10 NTU in lakes like Doddabommasandra and Shivapura suggest elevated levels of suspended particles. The diversity of bird and fish species varied widely across lakes, with Ulsoor Lake showing the highest diversity 
  • These numbers highlight the diverse ecological dynamics and pollution impacts that the Lake Health Index (LHI) project aims to capture and address for effective lake management and conservation efforts

Read more: Utilise treated wastewater: Bengaluru’s first water balance report

Inference from the pilot

Conventional wisdom suggests that rainfall, as a natural diluent, should mitigate pollutants in urban water bodies like lakes. However, in Bengaluru, rapid and unplanned urbanisation has disrupted this notion. The sophisticated network of stormwater drains, or rajakaluves, designed to transport rainfall away from urban areas, as well as sewage lines are plagued by systemic problems. During severe rains, these drains frequently overflow, flooding the surrounding area with untreated sewage. This overflow introduces raw sewage directly into lakes. Rather than mitigating pollutants, the initial rains of the season exacerbate pollution levels in these water bodies. This phenomenon underscores the urgent need for effective stormwater management and highlights the complexities of urban environmental dynamics in Bengaluru.

The resultant application, developed by Bengaluru-based startup Digital Pitaa, is a sophisticated tool for ongoing lake health assessment. It provides stakeholders with actionable insights and fosters  collaborative engagement among diverse stakeholders, including government bodies, to address identified challenges comprehensively.

The LHI project represents a collective commitment to environmental stewardship and sustainability. By harnessing the power of citizen science and digital technology, the initiative holds the promise of transforming Bengaluru’s lakes into vibrant and resilient ecosystems that benefit both present and future generations. The success of this project hinges on continued collaboration among stakeholders to ensure the long-term health and vitality of Bengaluru’s lakes as cherished natural resources for all.  

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  1. balappa Muniraj says:

    All lakes are to be under single DISTRICT LAKE AUTHORITY, and they should be solely responsible for the water quality and safe guarding the lakes.

  2. Shankar rao says:

    Commendable initiative of assessing lake health by concerned entities.should be extended to as many lakes as possible in the three valley systems of the city.i am sure with many companies to provide money from csr source. And mobilizing willing youth power for the noble work should not be a problem. There is no mention of a. Testing for organic impurities b.jeavy metal contamination, c. Identification polluting sources like surrounding development letting raw sewage flow into lakes and industries letting out water contaminated with untreated/partially treated inorganic pollutants.

  3. Professor K S Bhat says:

    should be extended at all lakes and monthly testing and reporting should be done by an independent body

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