Policy to fill lakes in parched districts with treated sewage water from Bengaluru continues
The Karnataka government has proposed a ₹1,670 crore project to supply treated water from Vrishabhavathi river in Bengaluru to regions like Tumakuru, Nelamanagala, Chikballapur and Doddaballapur, among others, to help revive depleting water tables in what appears to be the continuation of a policy to supply used water to regions surrounding India’s IT capital, officials privy to the development said.
JC Madhuswamy, Karnataka’s minister for minor irrigation, law and parliamentary affairs, said that the department has sent the detailed project report (DPR) to the government for its approval.
While the river, which resembles a drain, itself was lost to apathy, unchecked flow of sewage water and industrial pollutants, the new programme is meant to salvage the drain inlets by treating them and pumping around 300 mld (million litres per day) to nearby regions, outside of Bengaluru.
“Around 308 mld of secondary treated water will be used to fill up tanks in Chikballapur, Nelamangala, parts of Tumakuru and Doddaballapur,” a senior official at Karnataka’s minor irrigation told Hindustan Times.
Successive governments in Karnataka have pursued a policy to prioritise Bengaluru’s insatiable thirst by depriving regions around it. Not to say that Bengaluru does not have a water scarcity problem as most parts of the city are fed with tankers that are filled by overexploiting borewells that also harmed groundwater tables.
The closest river to Bengaluru is over 100 kilometres away which has forced governments to continue spending thousands of crores to bring this water to the city and its over 12 million residents.
Estimates by the Indian Institute of Science (IISc) states that Bengaluru receives around 700-850 mm of rain each year which is enough to accumulate around 16 tmc ft of water which is almost 70% of its demand of around 19 tmc ft. But the lack of treatment plants and awareness has given rise to a situation where most of the water is let out into drains by most households except large apartment complexes where it is mandatory to have sewage treatment plants.
The Siddaramaiah-led Congress government had initiated the Koramangala and Challaghatta Valley (KC Valley) project to pump around 440 mld of secondary treated water to Kolar and Chikkaballapur, drought-prone districts, to fill up lakes and tanks. The treated water was pumped into Lakshmisagar lake in Narsapura of Kolar directly. The project had raised a clear divide between the politically backed groups and scientists who argued the benefits and harms of such an exercise.
TV Ramachandra, a scientist at the Centre for Ecological Sciences at the Indian Institute of Science-Bengaluru said that “such projects are good if we are ensuring removal of heavy metals from water.”
Ramachandra, who has authored several papers on the water in Bengaluru, said that the Vrishabhavathi belt has a dense population of industries that discharge heavy metals into these streams, which would enter the humans through any produce grown with this water.
“We are so irresponsible as a regulatory body that we allow the industries to pollute the water bodies,” he said.
The official cited above said that the water from Vrishbhavathi will be used only to fill tanks and not for agriculture or drinking purposes.
However, experts do see a problem with such an approach that does not prioritise tertiary treatment of wastewater.
The primary treatment removes large particles, chemical ions are removed in the secondary treatment and nutrients are removed in the tertiary treatment, experts said, pointing out the requirement to carry out all three processes to make the most of water.
However, inadequately treated water into tanks to rejuvenate groundwater tables is unlikely to have the desired effect.
“Vegetables that are grown downstream and also the lake water have heavy metal contents. Those vegetables like pudina (mint) and spinach which we eat will naturally get into our body. Higher instances of heavy metals in our food items are also leading to the escalation in cancers and kidney failures in the region,” he added.
Ramchandra said that instances of kidney failure in the city (Bengaluru) which was 1 in 100,000 about 12 years ago stand at around 1 in 5,000 today.
The Bruhat Bengaluru Mahanagara Palike (BBMP), the city’s civic body, has also prioritised aesthetics over the quality of water in its periodical lake rejuvenation projects, experts said.
A report by CSIR-National Environmental Engineering Research Institute (NEERI) indicated that there are around 21 lakes out of the 205 existing on paper in which the water was fit for drinking.
This claim has been contested by environmentalists, scientists, citizens among others.
A report by the Karnataka State Pollution Control Board (KSPCB) in 2020 states that there is not even one lake that has water fit for drinking. But fish from these lakes are often consumed in Bengaluru as the licences are auctioned to the highest bidder. In Bengaluru’s BTM Lake, people throng to buy fish like Rohu (Labeo Rohita), Catla (Labeo Catla) and the common carp (Cyprinus carpio) among others in kilograms almost every weekend.
Several citizen-initiative groups have aired their concerns over such projects that focus on cosmetic and beautification rather than improving the ecology of the spaces.
A July 2021 research paper, titled, “Heavy metal in the food chain-Consequences of polluting water bodies” by TV Ramachandra and N R Narayan, studied the concentration of heavy metal in Varthur lake, near the technology corridor of the city.
“The study on heavy metal concentrations in vegetables grown near Varthur lake, Bangalore, has shown significant accumulation of heavy metals in vegetables that correlated well with its soil and lake water concentrations. The prolonged irrigation of vegetables using such contaminated lake water has led to soil contamination, which ultimately resulted in contamination of vegetables due to the uptake and accumulation of heavy metals in edible portions of vegetables. The heavy metal content in vegetables exceeded the safe limits in India,” the paper stated.