Consistent rain this season has not only filled lakes in western parts of the city with water but also with weeds and waste from upstream. The Water Resources Department is removing truckloads of vegetation that has overgrown in lakes like Retteri.
The chain of waterbodies in Ambattur, Korattur and Retteri have already reached their full capacity. However, these lakes are covered with a thick layer of water hyacinth after the intense rainspell early this month.
An official of the WRD said: “Nearly 25 truck loads of weeds and waste were removed from Retteri lake alone over the past 10 days. We had already carried out the work as part of monsoon preparedness. But, loads of weeds had reached the lake from upstream through surplus courses and other drains.”
The growth of weeds indicate sewage pollution in the waterbodies. Despite restoration efforts, Ambattur lake continues to be vulnerable to the disposal of untreated sewage from local bodies like Ayapakkam.
Many of the neighbouring local bodies still lack proper underground sewer network and hence waterbodies turned a target for sewage discharge. Polluted water too got conveyed along with floodwater to the lakes downstream and led to the growth of weeds. Such menace can be put to an end only when the surrounding localities get a sewer network, officials said.
The three lakes together have a storage capacity of 500 million cubic feet and surplus water from Retteri joins Red Hills reservoir’s surplus course. “We convey the waste and weeds removed from the lakes to Kodungaiyur dumpyard as of now,” the official added.
The WRD continues to release 1,000 cusecs (cubic feet per second) of surplus water from Red Hills reservoir into the surplus course that joins the Ennore creek. Nearly 2,000 mcft of floodwater have been drained into the sea. Moreover, floodwater from Retteri too joins the channel.
Though the course has a capacity to carry 7,000 cusecs, some of the low-level areas downstream get waterlogged when the course carries half its capacity. The stormwater drains are often connected at bed level instead of the channel’s maximum flood level. The SWD do not function during the rainy season as the channel is already flowing with floodwater and there is reverse flow from the SWD, waterlogging the nearby localities, officials added.