With frothing in Thenpennar and Palar rivers on the rise, TNPCB seeks Anna University's help

CHENNAI: With frothing has become more common in Thenpennar and Palar rivers during the monsoon season, the Tamil Nadu Pollution Control Board (TNPCB) is puzzling over the types of pollutants and their sources. So, the State Environment Department has directed the TNPCB to engage Anna University to study reasons behind the foam.

A TNPCB source privy to the development said that the University will be paid around Rs 50 lakh to conduct the study.

“As the work will be handed over to another government body, there is no need for floating tenders. The University will commence the study once official orders are issued,” the source added.

The development is due to the frothing in Palar river near Ambur, Tirupattur district, and an order issued by the southern bench of National Green Tribunal (NGT). Despite several frothing incidents in both the rivers that originate from Karnataka, the TNPCB could not ascertain the reason for the incidents correctly.

On the other hand, an expert in river pollution working with the government, explained that frothing occurs when a fast flowing river carries pollutants and hits the curves. “This will agitate the pollutants. Both the rivers have too many curves. Ironically, there is no equipment available in the State to find out the exact composition in froth,” he added. “Traditionally, the TNPCB would collect samples of the river and test it for total dissolved solids (TDS), biological oxygen demand (BOD), chemical oxygen demand (COD), heavy metals and other parameters. But, those tests will not give results in frothing incidents.”

He also explained that the foam composition will only be identified if TNPCB officials collect the foam instead of the water. “An-ion and cat-ion tests should be done to detect ions. This will provide details about the chemicals. Also, tests to detect carbon chains are necessary to ascertain the pollutants,” he pointed out.

Meanwhile, rankled by the failure of the pollution control boards of Tamil Nadu and Karnataka to control frothing in the rivers, the southern bench of NGT reopened a case a few days ago, which was closed in June 2021, with directions to both governments to improve water quality in the river. Recalling a frothing incident in October this year in Kelavarapalli Reservoir (across Thenpennar), the Tribunal observed that if the State authorities had complied with the directions issued by the Tribunal, such incidents would not have recurred.

The NGT also directed the chief secretaries of both states to file their reports about the compliance with the earlier orders that were based on a joint committee report formed in 2020. The committee had pointed out discharge of domestic sewage and industrial effluents from Bengaluru, apart from providing recommendations to improve the water quality.

Due to non-compliance and further river pollution, the Tribunal, in July 2022, directed the chief secretaries to file the minutes of the periodical review meetings once in two months. “But, it has not been filed,” the Tribunal observed.

Being the biggest basins after the Cauvery river, Thenpennar and Palar are the lifelines of north Tamil Nadu districts. Flowing through Dharmapuri, Krishnagiri, Tiruvannamalai, Cuddalore, Kallakurichi and Villupuram districts, Thenpennar, the second longest river in the State, is the drinking water source to those districts.

Meanwhile, flowing through Vellore, Tirupattur, Ranipet, Kancheepuram and Chengalpattu districts, Palar is also a major source of drinking water and irrigation in the districts. A few areas in southern suburbs of Chennai receive drinking water from the river.