Catfish signals revival of city lakes: Untreated Sewage A Problem

Untreated Sewage A Problem, But Hauz Khas & Neela Hauz Being Cleaned

New Delhi: The recent discovery of a 3.5 feet long catfish in the shallow Hauz Khas Lake had marked a major progression in the revival of the lake, which till some months back had been a smelly cesspool of untreated sewage. Though residents still complain of foul smell from a part of the lake but its biochemical oxygen demand — an indicator of pollution levels — has dropped from 11mg/l to 6 mg/l in a span of six months. 
    A few kilometres away, Neela Hauz continues to languish under an onslaught of untreated sewage. Both water bodies have the same source of water — treated effluent from the Vasant Kunj sewage treatment plant and untreated sewage from Mehrauli and nearby areas. Neela Hauz, over which a flyover was constructed for the Commonwealth Games and should have been restored by October 2010, is nowsupposed to be restored by February next year as per a high court order. 
    Debris from the water body was just cleared last week and according to Delhi Development Authority officials, the water body will be restored by the court-set deadline. 
    Plantation will be carried out by next monsoon. While debris dumped by the PWD around the lake during the flyover construction has been removed, a lot of it that subsequently was dumped into the main water body is still to be cleaned out. 
    “The revival plans released by DDA show a much smaller area of the lake compared to what it was before the flyover project began. Our concern is not the peripheral work that DDA will get done on plantation etc. We only want that the water body is preserved properly, and for that untreated sewage must be stopped from entering it and secondly, the area of water should be increased,” said Nitya Jacob, a resident of Vasant Kunj. 
    According to Delhi Jal Board officials, they will be trapping untreated sewage from the Kishangarh area in Mehrauli and diverting it to Vasant Kunj STP. Some institutions, located near the lake, have been discharging their waste into it directly and they have been asked to take corrective measures. 
    The lake will finally be merged with Sanjay Van where efforts by residents have already seen some improvement in water quality of the lake there. 
    From Neela Hauz to Hauz Khas Lake, there are five check dams where residents of nearby areas have introduced fish. These catfish have found their way to Hauz Khas and feed on the carps that were introduced in the lake. 
    The check dams also act as regulators since anytime the flow of untreated sewage increases, they can be shut down. 
    “The Hauz Khas Lake is fed by treated effluent from the Vasant Kunj STP, some untreated sewage from the Mehrauli ward and rainwater. The north/northeast side of the water body is deeper and in the shadow zone — meaning it is protected from sunlight and wind. Hence it also looks dirtier. Other than bio-remediation, we have asked DDA to take water from the deep end for gardening, ensure that the pipe from the last check dam to the lake should always have water flowing through it and ensure that aerators work at the deep end,” said Manu Bhatnagar, the principal advisor of environment projects in Intach’s natural heritage division. 
    “We have seen a substantial change in water quality in the past few months,” he added. Intach is working in an advisory capacity with DDA to revive the lake. 
    The lake has started receiving migratory birds as well, but sources say that DDA officials are not following all instructions and untreated sewage often finds its way into the lake. 
    “The aerators are also not working and the part of the lake next to the monument is filthy and smelly,” said Rashmi Singh of Green Park.

Source: TOI (pg.9, 25 Nov 2012)