Guwahati, Aug 19: As floodwaters recede across parts of upper Assam, a new environmental threat in the form of plastic waste and worsening water quality is emerging in its wake. More than 1,200 kg of plastic waste has already been collected from flood-affected areas of Sivasagar and Charaideo, with packaged drinking water bottles making up a major portion of the waste. The Assam Pollution Control Board (APCB) has engaged three NGOs for the collection drive, with recycling vendors and gaon panchayat-level workers also joining the effort. The large-scale collection comes as residents in flood-affected areas increasingly depend on packaged drinking water amid concerns over the safety of local water sources. Relief materials distributed during the floods have also added to the volume of plastic waste, particularly through packaging and bottled water. While the immediate focus is on clearing the accumulated waste, officials are also assessing the impact of the floods on water quality across affected areas. Water samples have been collected and sent for testing, with initial examination showing a decline in dissolved oxygen (DO) and an increase in biochemical oxygen demand (BOD) and chemical oxygen demand (COD). A fall in pH levels has also been recorded. The changes in DO and BOD are of particular concern. Lower dissolved oxygen can place aquatic organisms under stress, while elevated BOD indicates a higher concentration of organic pollutants in the water and greater oxygen consumption by microorganisms. “These parameters are not within prescribed standards and may affect aquatic life. Further analysis is being done,” an APCB official said. Officials said residents have also reported changes in groundwater drawn from bore wells and tube wells, including an unusual smell and change in colour. The results of tests for heavy metal contamination are still awaited. Meanwhile, the plastic collected under the clean-up drive is being handed over to recycling vendors for processing. Authorities said efforts are being made to ensure the recovered material does not end up in water bodies or open dumps. The scale of plastic recovery, alongside the early signs of deteriorating water quality, has added a new environmental dimension to the post-flood clean-up in Upper Assam.