State Pollution Control Board says water unsuitable for potable purposes
The lake in Udhagamandalam, popularly known as Ooty, is, according to a study by the Tamil Nadu Pollution Control Board (TNPCB), one of the most polluted water bodies in the State. Its water quality, the study says, is unsuitable for potable purposes.
A major tourist attraction in the popular hill station, the lake now emits a foul odour, thanks to untreated sewage being let out into it.
An analysis of water samples from the lake conducted by the TNPCB revealed that the presence of biochemical oxygen demand (BOD) in the Ooty lake has exceeded prescribed standards, at 11 milligram per litre (mg/l) as against the tolerance limit of 3 mg/l. The level of BOD is used as an indication of the organic quality of water, and defines the degree of organic pollution.
The study also found that the total and fecal coliform contamination levels stood at 5,353 (most probable number in 100 millilitres) and 10,322 MPN/100 ml respectively, which is more than double the permissible limit.
TNPCB has been monitoring the quality of water in the lake under the Central Pollution Control Board’s ‘Monitoring of Indian National Aquatic Resources System’ programme. At present, 55 water quality monitoring stations function across the State.
Residents of Udhagamandalam said the Ooty lake, once a freshwater source, has been reduced to a sewage cesspool.
R. Babu, a resident of Church Hill, Udhagamandalam, said that sewage from several parts of Ooty had been channelled into the water body that is now partly covered with water hyacinths. Garbage is also dumped on its bund.
“I have stopped going on boat rides in the lake as it smells so bad. Many residents hesitate to go boating as the stagnated water is contaminated. The government must take measures to prevent raw sewage from entering the lake,” he said. Samples of water taken every month are tested at the TNPCB’s laboratories for various parameters, including the level of total hardness, total dissolved solids and magnesium.
Among the eight water bodies monitored, the water quality in Pulicat lake does not meet the criteria of prescribed standards. However, TNPCB officials said that the backwater intrusion bringing in seawater could be the reason for the poor quality of water in Pulicat.
Data analysis of the water bodies in Poondi, Porur and Red Hills, which serve as sources of drinking water supply to the city, reveal that they too are contaminated. Though they are defined as to be used as drinking water sources after treatment and disinfection, the tests show the presence of coliform bacteria in samples of untreated water.
The level of total coliform in the sample taken at Red Hills is 4,744 MPN/100 ml, close to the tolerance limit of up to 5,000 MPN/100 ml. The water body in Veeranam, from where Chennai receives part of its supply, is defined as to be used only for bathing.
Residents of Puzhal said that the Red Hills lake was often misused, as part of the water-spread area is not covered by a bund. The stretch near Ambattur Red Hills Road, for instance, is often used for bathing and washing. It is essential to step-up monitoring of the water body, they said.
Many of the State’s rivers too are polluted. According to the study, Palar river also has fecal coliform. But the water can be used for drinking after treatment.