‘Selaiyur lake water unfit for drinking due to sewage discharge’

“We have sent the samples for water quality after the monsoon season. Biological oxygen demand (BOD5) value is higher than the tolerance value of 3mg/l for class C surface water in 6 out of 7 samples.The results indicate a high level of organic matter enrichment due to the discharge of raw sewage into thelake,” said Darwin Annadurai, volunteer at Eco Society of India. “The government should make an alternative way to discharge sewage, since, due to this, the groundwater in the locality is also contaminated,”he added.

Surface water in natural environments contains a small quantity of organic compounds. But in an urbanised centre like in Selaiyur, heavy inflow of sewage brings in loads of nutrients to the water bodies which is consumed by the micro organisms present in the water utilises dissolved oxygen in the water, activists pointed. The demand for oxygen increases, leading to mass fish deaths in the waterbody and these lakes will become like Adyar and Cooum. It is a common problem faced in urban areas.

“There was some suggestions to pour some chemicals to purify the lake dirty water. But it is effective and feasible only for small ponds. Not effective or feasible for such a large water body. Moreover, it is not a permanent solution or the best option,” said Saravanan K, another volunteer.

The Water ResourcesDepartment (WRD) said that they will soon set up a sewage treatment plant (STP) in the lake. A senior WRD official said, “We are in process in restoring the water bodies in the city. As part of the project, we will be installing STP to stop sewage entering into the lake.”