Only one lake in Bengaluru fit to be drinking water source after treatment

Water quality of all but one falls under D and E categories in latest classification by KSPCB

Several fish were found dead at Kothnur lake due to pollutants early this month. | Photo Credit: K. MURALI KUMAR

Multiple schemes, many promises and years later, the state of lakes in the city remains the same sordid tale of pollution, neglect and degradation. The latest classification of water quality in lakes in Bengaluru from April 2021 to March 2022 by the Karnataka State Pollution Control Board (KSPCB) shows that all but one lake in the city failed to make it beyond the last two categories.

The only lake that fell under the C category (drinking water source with conventional treatment followed by disinfection) was Allasandra lake, which saw an improvement in water quality in March this year.

Over the period, 851 samples fell in the D category (propagation of wildlife, fisheries), 279 fell under the E classification (irrigation, industrial cooling, controlled waste disposal). None made it to the top two categories (A: drinking water source without conventional treatment but after disinfection, B: outdoor bathing - organised) .

Lack of integrated approach

One of the main reasons why efforts and budget allocations for rejuvenation of lakes has not borne fruit is because of lack of integrated approaches in management, said T.V. Ramachandra, Coordinator, Energy and Wetlands Research Group, Centre for Ecological Sciences, Indian Institute of Science.    

“Untreated sewage continues to flow into the rejuvenated lake, with other issues such as dumping industrial effluents into the lake, solid waste in the lake bed, dumping of construction and demolition waste. Active participation of local people in the management of lake - such as in the case of Jakkur lake - during the post-restoration period would certainly help in maintaining the quality of urban lakes,” he said. 

Prof. Ramachandra’s team monitored 40 lakes distributed across the three major watersheds - Koramangala and Challaghatta valley, Vrishabhavathi valley and Hebbal valley - which were grouped under three different WQI status - good water quality (10%); poor water quality (37%) and very poor water quality (53%). The majority of restored lakes have become polluted, indicating improper decontamination and poor maintenance of restored lakes, they pointed out.  

Impact on food and water

Scientists have pointed out why we should be worried; poor condition of lake ecosystem will severely impair fish, fodder and water, lead to propagation of invasive species and contamination of groundwater - evident from higher levels of nitrates in the borewells.

“A serious concern is the presence of heavy metals in our food. A study on heavy metal concentrations in vegetables grown in the command areas of Varthur  and other lakes in Bengaluru has shown a significant accumulation of heavy metals in vegetables that correlated well with its concentrations in soil and lake water,” said Prof. Ramachandra.

W He pitched for an independent authority for lake conservation and management and making this accountable for lapses in restoration, implementation of the “polluter pays principle” stance, and making bureaucracy accountable for ill-conceived projects affecting lakes.

KSPCB’s role

Citizens also raised questions about the role of the KSPCB. V. Ramprasad from Friends of Lakes said the board’s responsibility is not just to indicate or publish the water quality, but primarily to control pollution that is resulting in poor quality water. “It is also the primary fundamental responsibility and duty of KSPCB to identify the polluters and legally prosecute them. Action taken reports to improve the water quality grades should also be published,” he said.

Mr. Ramprasad also said instead of simply publishing the grades, if the parameters of water quality that have failed could be mentioned, then it would be helpful for citizen lake groups to work on remedial measures.

Quality of river water also of concern

In what could be more worrisome, the highest number of water quality samples from rivers in the state fell in the C category . While 753 samples were C category, 190 were under B. None fell under A, and 128 and 18 were under D and E respectively.

Recently, a new study by the IISc published in the journal ‘Ecotoxicology and Environmental Safety’ had revealed that pollutants like microplastics may be causing growth defects in fish, including skeletal deformities in the Cauvery river.

Scientists have blamed sustained discharge of  untreated industrial effluents, disposal of untreated sewage of surrounding towns, removal of riparian vegetation (aiding in remediation of surface run-off), degrading catchment and apathy of local administration, as major factors.