Trouble runneth deep in dying Adyar, Cooum rivers

CHENNAI: On July 30, when you happen to watch the Olympics triathlon event on television, you may sigh in disappointment at not being able to take at least a walk along the Cooum or Adyar rivers.

Exactly 101 years after the authorities in Paris officially banned swimming in the Seine River due to high pollution, the city is all set to hold triathlon events in the river as a part of Olympics 2024 and allow the public to swim in the now cleaned up waters. As per reports, the cleaning was completed in just 8 years.

In contrast, Adyar and Cooum rivers, even after earmarking thousands of crores of rupees to clean up the rivers and a lapse of 18 years, remain one of the most polluted river stretches in the country.

In January 2023, the Central Pollution Control Board (CPCB) revealed that Cooum River in Chennai is the most polluted river in the whole country and the number of polluted river stretches in Tamil Nadu increased to 10 in four years.

As per the CPCB, biochemical oxygen demand (BOD) in Cooum River between Avadi to Sathya Nagar was 345 mg per litre, which is the highest value among 603 rivers in the country that were assessed. On the other hand, Adyar river - between Tambaram to Nandanam - had a BOD value of 40 mg per litre.

Biochemical Oxygen Demand is applied to determine the aerobic destructibility of organic substances. BOD is the biological method used for the measurement of the total amount of dissolved oxygen (DO) used by microbes in the biological process of metabolizing organic molecules present in water. In other words, higher the BOD value higher the pollution. Rivers with higher BOD would not support biodiversity. BOD value more than 3 mg per litre is considered as pollution.

Following the revelation, the Ministry of Jal Shakti constituted the Central Monitoring Committee as per the order of National Green Tribunal (NGT) to oversee the cleaning of the polluted rivers including Adyar and Cooum. During a monitoring committee meeting, Chennai Metropolitan Water Supply and Sewerage Board (Metrowater) apprised that projects, including underground drainage works in newly added areas, at an estimated cost of Rs. 3,000 Crore are ongoing. However, there is a huge disparity between the amount of water utilized in the city and the amount of sewage treated by sewage treatment plants run by the Metrowater. As per Metrowater claims, the city has a STP capacity of 1,082 million litres per day (MLD) and average sewage collected in STPs is 600 MLD. On July 22, as much as 660 MLD of sewage was pumped by pumping stations but 592.92 MLD was received and treated in STPs. To put into perspective, the water manager had supplied 1,095 MLD of drinking water to the city, which is excluding the amount of groundwater extracted by the residents for daily usage.

At the meeting, the Committee expressed displeasure over the non-comprehensive response being received from the State officers. The state officers could not respond to the queries raised in the meeting and update the status to the Committee. Following this, the committee directed the state government to be represented by higher officials well versed with the subject.

The two rivers remain in the sorry state of affairs despite the formation of Chennai Rivers Restoration Trust (CRRT) in 2006 and several close monitoring of NGT. In July 2015, the green tribunal directed the state chief secretary to convene a meeting once every two months to review the progress of the river restoration projects along with the line departments. Directions were also given to submit the minutes of the meetings through CRRT.

Soon after identifying the Cooum as the most polluted river and Adyar as one of the highly polluted rivers, the CPCB has also directed Tamil Nadu Pollution Control Board (TNPCB) to prepare action plans on a priority basis to clean up the rivers. Even after 18 months, the action plans are yet to be prepared.

The action plans should be prepared by collating action plans of other departments like Chennai Corporation, Metrowater (Chennai Metropolitan Water Supply and Sewerage Board), Water Resources Department and others. If the sources are to be believed, the action plans are delayed due to lack of coordination among the departments. Irked by the lackadaisical attitude towards the cleaning up of the rivers, the Ministry of Jal Shakti has asked the state government to provide a deadline for the completion of the works.

Rs. 4,770 Crore project for Adyar river:

Meanwhile, chief minister MK Stalin has approved Rs. 4,778.26 Crore for rejuvenation of Adyar river. Under the project, the 44-kilometer-long river will be restored by CRRT. The government has also established Chennai Rivers Transformation Company Limited, which will function under CRRT, to oversee the restoration of the river.

Adyar restoration projects include the installation of a 70-km sewage pipeline along the riverbanks, construction of 14 sewage treatment plants with a total capacity of 110 MLD, and the development of four parks to enhance green spaces along the river. The project, slated for completion within 30 months, includes provisions for maintaining the river for 15 years.

Under CRRT, the Greater Chennai Corporation has installed 3 trash boom systems at Kotturpuram, Maraimalai Adigal Bridge and Jafferkhanpet. On the other hand, Metrowater constructed interceptor and diversion pipelines and modular sewage treatment plants. The Tamil Nadu Urban Habitat Development Board has identified 9,539 families to be evicted from the banks of the rivers, of which 4,743 families have been resettled.

Apart from this, the government has given administrative sanction of Rs. 735.08 Crore for the implementation of Integrated Cooum River Eco-Restoration Project (ICRERP) to restore the river from Paruthipattu check dam to the Cooum river mouth for a length of 32 kilometres. Also, an administrative sanction of Rs. 1,281.88 Crore for restoration of Buckingham Canal and its associated drains, and major drains of Adyar and Cooum River.

There is a ray of hope:

Hopes are not completely lost for Cooum and Adyar as concerted efforts by the government departments have fructified right here in Tamil Nadu (why go to Paris?). In 2018, CPCB included Cauvery, Bhavani and Tamirabarani rivers in the list of polluted river stretches as the rivers had BOD of 17, 4.6 and 7.5 mg/L respectively.

The BOD levels were too low when compared to Cooum and Adyar, but the government improved the water quality to bathing standards. After the restoration works, BOD in Cauvery and Bhavani were improved to 3 mg/L and Thamirabarani recorded a BOD level of 2.5 mg/L. BOD level up to 3 mg/L is considered a bathing standard. BOD value more than 3 mg/L is considered as pollution.

Apart from Cauvery, Bhavani and Tamirabarani, the BOD levels of Sarabanga, Vasistha and Thirumanimutharu have also been improved. In October 2023, the BOD levels of the rivers were 12, 6 and 7 mg/L respectively. As per 2018 report, BOD levels were 24 mg/L in Sarabanga, 56 mg/L in Thirumanimuthar and 230 mg/L in Vasistha river.

According to a policy note of the Municipal Administration and Water Supply department, eco-restoration of 58 acres of Adyar Creek and 300 acres of Adyar Estuary was taken up under Chennai Rivers Restoration Trust (CRRT). After the restoration, 358 acres of creek and estuary house as many as 424 species including molluscs, crabs, dragonflies, butterflies, fishes, amphibians, reptiles, birds and mammals. Before the restoration, there were only 141 species in the region.

It may be noted that the government allocated Rs. 100 Crore for the eco-restoration of Adyar Creek and Estuary on the eastern side of Thiru Vi Ka Bridge as the ecological sensitive region was degraded due to Prosopis juliflora, indiscriminate disposal of sewage, solid waste and debris which subsequently resulted in shrinking of water spread area, reduced tidal interaction and decrease in biodiversity.

Committee to ensure free flow of Cooum:

With the northeast monsoon nearing and the restoration of Cooum to take more number of years and debris dumped in many spots inside the river to carry out Port-Maduravoyal Elevated Corridor project, the MAWS department has decided to form a coordination committee to ensure free flow of water in Cooum river during the monsoon.

Officials from the Chennai Corporation, Metro Water, public works department, water resources department, disaster management and others will be included in the committee.

When asked, P Senthil Kumar, secretary of Environment, Forest and Climate Change department, said, “The works to restore the rivers are ongoing at a good pace. The MAWS department is coordinating the clean-up works.”