Muddy waters of Cooum and Adyar rivers to get a new lease of life

Recently, the Madras High Court had directed the Tamil Nadu government to restore the Adyar and Cooum rivers to their past glory. While Phase I and Phase II of the Adyar river restoration have been completed, and Phase III is yet to begin, there has been some headway in the restoration of the Cooum, over the last two years. Experts say that the various challenges to restoring a river include dealing with the quantum of sewage flowing into the waterbody, lack of a holistic and concentrated effort from all the stakeholders involved. 

After multiple failed efforts over decades to clean up the Cooum, the government appointed Chennai Rivers Restoration Trust (CRRT), a nodal agency to bring in the different departments together to execute the restoration. The ecological restoration focusses on the stretch from Paruthipattu Anicut, at which point the river is heavily polluted, to the river mouth. The biggest problem affecting the river is that of untreated sewage. A study by LKS India Pvt Ltd done before the restoration process, identified raw sewage outfalls along the river: flow through storm water drains (SWD) (73), overflow from sewerage (19), flow directly from premises (16), SWD dry (9) and sewage treatment plant (1). In addition, thousands of sewerage pipelines were illegally connected to storm water drains, directly dumping the sewage into the river. To tackle this, Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) is in the process of enlarging underground sewerage system (UGSS) while sewage outfalls will be plugged through 16 km of interception and diversion pipelines.  

An official from CRRT pointed out that as the city grew, so did the sewage. “The sewage flow increased and eventually, it was diverted through SWDs into the water bodies. The CMWSSB is in the process of laying interceptor pipelines to divert the sewage to the nearest pumping station, where it will be treated,” said the source.  

“The removal of the dumped waste is being carried out by the Greater Chennai Corporation while the major drains are being desilted by the Public Works Department (PWD) and the river mouth. The laying of the boundary stone is also currently underway,” added the source. There has also been a proposal for the river front development.  

Sudhir Chella Rajan, Professor, IIT Madras, who had carried out a social survey of the Cooum, said, A lot of illegal dumping happens upstream and septic trucks too are emptied in some places, which are industrial effluents,” she said. 

Dr Ligy Philip, Professor, Environmental and Water Resources Engineering Division, IIT Madras, had conducted a study in 2015 on pollution along the Adyar river, and the water quality in 20 locations was analysed over a period of oneand-a-half years. “Not much thinking or effort has gone into the basic reasons for river pollution. Unless the cause of pollution is found and addressed completely, the river cannot be restored,” she said.

River restoration is hampered by a lack of data, said Dr Latha Anantha, Director, River Research Centre, Thrissur, Kerala. “We don’t have authentic data on any of the parameters that are important for restoring our rivers. Restoration should look at a river holistically, identify vulnerable aspects based on data and involve the community in a concerted effort. It requires a good sense of ecology of the river,” she concluded. 

Provide adequate treatment facilities to ensure quality of domestic waste water coming to the river from its catchment area. 

Improve sanitary facilities, solid waste/ garbage disposal facilities for the community living on the banks and catchment area of the river.

Keep mouth of river open to allow mixing of river water with sea water.

One time removal of settled debris, solid wastes and sediment deposit on the banks and river mouth.

Design wetland to reduce loading from effluents.

Provision of infiltration trench along the length of the river to reduce the pollution loading from storm water runoff.

Provision of dhobi ghats near the river and treatment of the effluent before discharging to river