Bellandur can wait no more

Frothing and on fire, Bengaluru’s biggest waterbody, the Bellandur lake has shot off another warning sign of its terminal illness. Polluted beyond half-hearted redemption efforts, the lake’s message is unquestionably clear: Long stuck in planning, the revival plans have to take off. Now!

In its wide expanse of 379 hectares, the lake under the Koramangala – Challaghatta Valley receives over 40% of the city’s mostly untreated sewage. This has triggered pollution so extreme that it has turned the water toxic, contaminated the groundwater all around and played havoc with the ecosystem.

Incessant sewage inflow
Incessant inflow of heavy metals through sewage and storm water drains has pushed the lake to almost a point of no return. Every settlement around the lake is at risk, the water and air around thick with health hazards. Death and despair looms in its vicinity.

But the danger goes beyond. Irrigated with the toxic water, vegetables cultivated on the banks of Bellandur and Varthur lakes find their way to the city’s markets. So do the fish. 

Enriched by the pollutants, the proliferating water hyacinth on the lake surface is a clear sign of the decay, both visible and underneath. As Karnataka State Pollution Control Board (KSPCB) informs, the hyacinth blocks sunlight from penetrating the surface, dramatically reducing the Dissolved Oxygen (DO) levels.

Alarming water quality
Water quality parameters monitored at three different locations in Bellandur lake by KSPCB in December 2016 gave out alarming results: “Except water temperature, pH and lead, all other parameters were beyond the tolerance limits,” analysed the Board.

The DO levels had dipped to 2.20, 2.36 and 2.66 milligrams / litre at the three points, way below the > 4 mg/l optimum range. Biochemical Oxygen Demand (BOD) concentration, at 10.96 to 12.28 mg/l was at least four times higher than the limit of less than 3 mg/l.

The Carbon-dioxide (CO2) concentration was also extremely high, while Nitrate Nitrogen and Phosphate Phosphorus were two times higher than the optimum range.
In its report, an expert committee on rejuvenation of Bellandur lake, has acknowledged the poor management of waste water flowing into the lakes. “The lakes have come to suffer abnormal levels of pollution,” it said.

Multiple pollutants
The pollutants were linked to septicity, obnoxious odour, aerosols with toxic volatile organic compounds, eutrophication, breeding of mosquitoes, disappearance of native fish species, algal bloom, and profuse growth of invasive exotic aquatic macrophytes.  

The local community had also complained to the panel about water-borne diseases and contaminated borewell water. “The committee is convinced of the problems faced by the local biological entities (humans, livestock, etc.) of serious water and soil contamination and consequent impacts in the food chain.”

The biggest cause of pollution was clearly the release of untreated sewage, poorly treated industrial effluents and domestic sewage into the lake.

Inefficient STPs
Over the years, 252 residential apartments have sprung up in the Bellandur catchment area. Many of them have installed Sewage Treatment Plants (STPs), although treatment efficiency is questionable. “An estimated 480 MLD of total waste water flows in the catchment area, partly treated by the STPs,” the report says.

So, what has been done so far to translate plans to action? The Bangalore Development Authority (BDA) says tenders are being floated for deweeding and installation of aerators in the lake. These measures are critical to remove the macrophytes /hyacinth and boost dissolved oxygen levels inside the waterbody.

Community consensus
For years, the local community, lake activists and Indian Institute of Science (IISc) researchers have been campaigning hard to work out some action plan to stem the lakes’ decay. But differences had cropped up on the method to be adopted. This has now been resolved, says Elangovan from Whitefield Rising.

An active citizen’s collective, Whitefield Rising now wants the short-term measures recommended by the expert panel to be immediately and simultaneously implemented for both Bellandur and Varthur lakes.

The panel had mandated that macrophytes have to be regularly harvested to curtail accumulation of nutrients, dumping of municipal solid waste halted and all waste processing units in the vicinity of the lakes evicted.

Jakkur lake model
The survey sketch for both Bellandur and Varthur lakes, says Elangovan, should be published immediately and the water bodies fenced. “These two lakes need to be desilted, macrophytes removed and treated waste water let in through the wetlands and shallow algae ponds, as is done for Jakkur lake.”

Not everyone is convinced that the lake panel's report will lead to concrete action unless the symptoms are identified and well-documented. Researcher Nagesh Aras suggests that the fire spots and garbage/construction debris dumping sites should be mapped.

Crowd-source evidence
Simply put, the need is to crowd-source the evidence by marking all the black spots on a map. Volunteers could take photographs of each black spot and upload them through their smartphones. This could be an anonymous exercise, says Aras.

The data thus collated with GPS-positioning could be furnished to the National Green Tribunal (NGT). Only then can a properly structured remedial action work. Or else, he warns, the  attention sparked by the fire and smoke will subside without a whimper.