The lack of sewage treatment plants has adversely affected the rejuvenation of several lakes in Bengaluru.
Sandeep Anirudhan, an environmentalist, said: “While sewage treatment plants for lakes are important, the real problem is the discharge of untreated sewage into storm water drains which ultimately ends up in lakes and affects the quality of water. Harmful microbes enter the lakes which increase the algae in the lake, depleting oxygen levels and affecting the ecosystem.”
“STPs need to be set at the source level itself and regulations need to be brought in. Efforts need to be made that sewage is treated before being sent to storm water drains,” he added.
Abhinandan, a resident of Sarjapur, informed The Observer: “The level of water in the Kaikondrahalli lake, near my house, has reduced. This is because sewage has been let into the lakes through storm water drains, affecting the health of the lake.
“All the lakes in the city should have an STP. Otherwise, the quality of water will deteriorate. Attempts to rejuvenate the lake will fall short without STPs,” he added.
Satish, a resident of Halasuru, said the condition of lakes can be improved if sewage treatment plants are set up. “Lakes across Bengaluru are in a terrible condition. This is because untreated sewage is let into lakes. That is deteriorating the quality of the water in the lakes. The problem can be addressed if sewage treatment plants are set up around lakes.”
BBMP chief executive engineer for lake development, BT Mohan Krishna, said: “BBMP has set up sewage treatment Plants for five lakes in the city, most of which are tertiary treatment plants. These are in Uttarahalli, Doddakere, Dasarahalli, and Mallathalli which are conventional STPs, while the one in Hirohalli uses soil biotechnology that can treat secondary sewage. We plan to set up more such plants for lake rejuvenation.”
Asked about declining water levels in lakes, he said: “Due to high evaporation and percolation losses, the holding capacity of the lakes has decreased. This is because partially treated sewage is let into the lakes. The STPs help to solve the problem to some extent, but other work that we do, such as desilting, deweeding, and strengthening of bunds, also helps in lake rejuvenation. We also divert the sewage downstream.”
The National Green Tribunal set up a committee headed by Justice N. Santosh Hegde to oversee the protection and rejuvenation of the Bellandur, Varthur and Agara lakes. The committee recently submitted its report to the NGT.
According to The Hindu, the committee’s report has an action plan for the rejuvenation and maintenance of lakes and guidelines on resources. It addresses issues of compliance and non-compliance of rules and regulations by stakeholders such as BBMP, BDA, BWSSB, minor irrigation department and the Karnataka State Pollution Control Board. Its recommendations include desilting, deweeding and diversion of sewage.