The absence of sewer lines in 1,700 unauthorised colonies — housing around 40 lakh people — in the national capital is one of the major reasons of pollution in the Yamuna, the monitoring committee set up by the National Green Tribunal (NGT) for overseeing cleaning of the polluted river has said.

The river — that is the lifeline of the city as it supplies drinking water to most parts — is almost dead with high levels of toxic chemicals. The committee said sewage, mainly faecal sludge from these colonies being directly emptied into the river, adds to extremely high levels of pollutants not allowing the water body to sustain life.

The two-member monitoring committee, in an official note to the Delhi government last month, stated that in the absence of a sewerage system in 80% of the unauthourised colonies and slum custers, faecal sludge is being directly emptied into the river.

Faecal sludge has 2,000 to 8,000 mg/litres of biochemical oxygen demand (BOD) load per day, which is much higher than the 150-300mg/litres BOD of sewage.

The BOD levels — oxygen needed by the river to sustain life — in Yamuna is alarmingly high.

This is because sewage from planned colonies goes to the sewage treatment plants (STPs) and is then drained into the river. However, sludge from the unauthourised colonies is collected in septic tanks by private contractors and is directly emptied into the river, thus adding to the BOD levels.

Around one-third of Delhi’s population is dependent on septic tanks for its daily sewerage needs, the committee said.

“The faecal sludge leeches into the groundwater thus ruining the environment. It is leading to destruction of land, water and drains, for which no compensation is being demanded by government authorities, who are responsible for enforcement,” it said in its note.

Of the 1,797, unauthorised colonies in the city, only 14% have been provided sewage pipelines. However, the functioning is poor, as residents are not willing to pay the charges for the same, it said.

The NGT had in July this year formed the monitoring committee and directed it to submit by December 31 an action plan on cleaning of the river.

The situation has been grim despite the faecal sludge and
septage management rules being put in place since February
2018. The committee had asked the state government to notify the rules.

When contacted the committee said, the rules were approved by the government and are expected to be notified soon.

“We were told that the notification is ready and will be out soon. Once the rules are notified, implementation will be the key,” said a committee member not wishing to be named.

First Published: Nov 26, 2018 09:39 IST