Polluted creek water entering DPS Flamingo Lake is threat to Navi Mumbai’s wetlands: study

The latest test commissioned by Navi Mumbai Environment Preservation Society and NatConnect Foundation shows alarming levels of contamination from the tidal inflow channel, raising fresh concerns over the sharp decline in flamingo sightings at the wetland in Navi Mumbai this season.

The test suggests Total Dissolved Solids (TDS) at 19,600 mg/l — more than nine times the permissible limit of 2,100 mg/l under IS 2490:1974 inland surface water standards. This indicates that polluted creek water entering DPS Flamingo Lake is a threat to one of Navi Mumbai’s most important wetlands, which forms part of the Ramsar-listed Thane Creek Flamingo Sanctuary ecosystem.

“The toxic mix of polluted tidal inflows and extensive blue-green algal mats appears to have pushed DPS Flamingo Lake towards an ecological tipping point,” NatConnect Foundation director B.N. Kumar, adding that there is an urgent need to expedite the final Government Resolution granting Conservation Reserve status to DPS Flamingo Lake and ensure stronger legal protection.

The findings reinforce concerns raised by earlier tests commissioned by NatConnect. A sample collected from the lake in March recorded TDS at an alarming 21,720 mg/l, while a drain discharging into the wetland showed TDS levels of 7,950 mg/l in April. The April sample also recorded Biochemical Oxygen Demand (BOD) of 36.4 mg/l, exceeding the permissible limit. All three samples failed to meet inland water quality standards.

“Flamingos can tolerate natural salinity, but they cannot thrive in waters carrying a cocktail of sewage, urban runoff and other contaminants. The deteriorating water quality is steadily eroding the lake’s ecological balance and shrinking its food base,” Navi Mumbai Environment Preservation Society representative Sandeep Sareen said.

Scientific studies, including research published in Nature Geoscience, have highlighted the long-term risks of altering estuarine hydrology, showing that human interventions in tidal systems can trigger feedback loops that intensify ecological stress by affecting water quality, sediment dynamics and biodiversity. For Navi Mumbai, the diminishing presence of flamingos at DPS Lake is more than the loss of a seasonal attraction. It is an early warning that one of the region’s most fragile wetlands is under growing stress.

The findings at DPS Flamingo Lake reflect a wider global concern. The UNEP-DHI Centre for Water and Environment, in its report Wetlands: The Unsung Heroes of the Planet, has warned that wetland loss has accelerated since 2000, with pollution, habitat degradation and unsustainable human activity driving rapid declines in wetland-dependent species.

Flamingos are particularly vulnerable because they depend on a narrow range of water chemistry and salinity conditions that sustain the algae, diatoms and microscopic invertebrates forming their food base.