Navi Mumbai: Laboratory tests conducted on water samples from three wetlands in Nerul have raised fresh concerns about ecological degradation, with activists pointing to severe pollution, poor tidal circulation and possible sewage contamination in key flamingo habitats.
The affected sites — DPS Flamingo Lake, the NRI wetland and T.S. Chanakya lake — function as satellite ecosystems to the Thane Creek Flamingo Sanctuary (TCFS), supporting flamingos during tidal cycles. However, activists said the wetlands are no longer functioning as active intertidal systems due to restricted water flow and rising pollution.
Water samples collected by the NatConnect Foundation and analysed at a Thane laboratory showed several parameters breaching safe limits, indicating a stressed and stagnant ecosystem. Total dissolved solids (TDS) ranged between 17,360 mg/L and 22,920 mg/L, far exceeding the 5,000 mg/L benchmark. The pH level crossed 9, indicating alkaline stress, while biological oxygen demand (14.8–23.6 mg/L) and chemical oxygen demand (47.5–73.5 mg/L) pointed to heavy organic and chemical pollution capable of depleting oxygen levels.
Rekha Sankhala of the Save Flamingos and Mangroves Forum said the findings indicate a serious decline in wetland health. “These water bodies are showing clear signs of distress, with pollution levels far beyond what such ecosystems can sustain,” she said.
B.N. Kumar, director of NatConnect Foundation, said the data points to a disruption in natural water exchange. “The readings suggest that tidal circulation has been compromised, which is allowing contaminants to build up instead of being naturally flushed out,” he said.
He added that field observations this season indicate fewer flamingos using these wetlands during the migration period.
Activists link the deterioration to both local stagnation and upstream pollution. Observations along the Belapur–Vashi stretch of the Panvel creek point to untreated sewage discharge, with visible inflows near the NRI complex.
“The contamination appears to be linked to polluted creek water entering these wetlands. This is not just an environmental concern but also a public health issue, considering fish from these waters are consumed locally,” said Jyoti Nadkarni, a social activist.
Environmental expert C.S. Jacob said the elevated BOD and COD levels are consistent with degraded creek water quality and warned that unless the quality of incoming creek water improves, the connected wetlands will continue to deteriorate. He added that untreated sewage and possible industrial discharge could be contributing to the problem.
Raj Pugalia, part of the monitoring effort, said restricted tidal flow is a key concern. “When natural water movement is obstructed, these wetlands start behaving like closed systems, which accelerates stagnation and pollution,” he said.
Activists also dismissed suggestions that bird activity could be responsible, pointing instead to sewage inflow and regulatory gaps.
Environmental groups have raised concerns over governance failures. Climate activist Nandakumar Pawar said planning and regulatory lapses have played a major role. “There has been little effective intervention despite visible degradation, and that has allowed the situation to worsen,” he said.
Bittu Sahgal, founder of Sanctuary Nature Foundation, said the issue raises broader questions about environmental stewardship. “We are witnessing the steady erosion of a natural heritage that should have been protected for future generations,” he said.
“It is deeply concerning that these wetlands have deteriorated to this extent. The implications go beyond biodiversity and could affect groundwater systems as well,” said environmental activist Pamela Cheema.
“These wetlands were once thriving ecosystems. What we are seeing now is a visible decline that needs urgent attention,” Sankhala said.
The issue has been escalated to the Prime Minister and the Maharashtra Chief Minister, with activists demanding restoration of tidal connectivity and strict checks on sewage discharge.
Sandeep Sareen of the Navi Mumbai Environment Preservation Society said the findings reflect the consequences of unchecked urbanisation. “What we are seeing is the cumulative impact of development pressures overriding ecological safeguards,” he said, describing flamingos as sensitive indicators of environmental change.
Meanwhile, the Navi Mumbai Municipal Corporation (NMMC) has initiated its own assessment. “Samples from the identified wetland locations have been collected and sent for laboratory testing. “We will take appropriate action once the findings are analysed,” an official said.