Water hyacinths turn brown after use of herbicides in Powai lake. (Vanashakti)
Water hyacinths turn brown after use of herbicides in Powai lake. (Vanashakti)

NGO in Mumbai objects to use of herbicides in Powai lake

NGO in Mumbai wrote to authorities stating that a dangerous herbicides should never have been used in a wildlife habitat
By Prayag Arora-Desai
UPDATED ON SEP 14, 2021 12:32 AM IST

A Mumbai-based environment group on Monday wrote to authorities, strongly objecting to the use of herbicides to clear the growth of water hyacinths in Powai lake. The Brihanmumbai Municipal Corporation (BMC) had in August floated a tender for removal of water hyacinths at Ganesh Ghat, Pawarwadi and other areas to make space for immersion activities during Ganesh Chaturthi.

“Our preliminary enquiries with locals have revealed that as part of the preparations for immersion of Ganpati idols, the lake boundaries are being cleared to facilitate easy and safe immersion of the idols. BMC is undertaking this exercise. This may be needed considering the safety aspect of the devotees as the lake is a crocodile habitat. However, the point of serious concern here is that instead of manual removal of the water hyacinth, a herbicide has been sprayed on the vegetation,” wrote Stalin D, director of non-governmental organisation Vanashakti, in Monday’s letter.

Herbicides typically contain a chemical known as glyphosate, which can pose adverse toxicological effects on flora and fauna, especially in aquatic ecosystems. Depending on the extent of use, it may lead to an increase in the water body’s phosphorus content, which in turn will lead to the proliferation of algae and exacerbate eutrophication. This can reduce the ability of zooplankton to reproduce in turn for other biodiversity to thrive.

“This kind of a dangerous chemical should never have been used in a wildlife habitat of a Schedule I protected species (Indian marsh crocodile) under the Indian Wildlife Protection Act (1972). We urge you to immediately direct the stoppage of this practice and take action against those responsible,” wrote Stalin in his letter, addressed to the Maharashtra Pollution Control Board, BMC and the forest department.

Satellite images and ground observations by environmentalists and citizens reveal that the issue of water hyacinths in Powai lake is worsening rapidly, with a large part of the water spread now having been subsumed under the growth of this invasive weed, which thrives in polluted environments – in this case, due to the dumping of raw sewage into Powai lake. Several citizens have previously drawn attention to this development, and called for a comprehensive plan to address the cause of these hyacinths, which are a clear indicator of environmental degradation.

However, it has also been cautioned that simply removing these weeds is not enough to restore the health of the lake.

“The water hyacinths no doubt reduce the levels of the lake and reduce its boundaries, but at the same time they also remove organic pollutants and heavy metals in the lake. If the hyacinths are removed without tackling the issue of pollution due to discharge of sewage, the move will be counterproductive,” Stalin explained, while also advocating for the area to be handed over to the forest department for safekeeping.

“It is most important that the entire area becomes a conservation zone under the custody of the forest department. A joint forestry model may be activated with the help of the forest department, BMC and other stake holders like the Indian Institute of Technology-Bombay, which abuts a large part of the lake, to conserve the area,” he said.

Forest department and MPCB officials as well as Ajay Rathore, chief engineer of BMC’s hydraulic department, did not respond to calls and messages seeking comment on Vanashakti’s letter.

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