A new scientific study has detected significant concentrations of microplastics in three high-altitude lakes in the Kumaon region of Uttarakhand, with pollution levels rising in areas that are more densely populated and heavily visited by tourists.
Researchers examined Nainital Lake, Bhimtal Lake, and Garudtal Lake three ecologically sensitive water bodies located at high elevations. Such lakes are particularly vulnerable to environmental stress because they respond quickly to changes in their surrounding watersheds.
Urban Pressure Reflected in Pollution Levels
Among the three lakes, Nainital Lake recorded the highest microplastic concentrations, ranging from 200 to 1,300 particles per cubic metre. Bhimtal Lake showed levels between 60 and 960 particles per cubic metre, while Garudtal Lake the most remote site with no permanent residential settlements nearby recorded the lowest concentrations, between 40 and 320 particles per cubic metre.
The study links these differences largely to population density and human activity. Nainital’s watershed supports nearly 27,000 residents, while Bhimtal’s has over 8,000. In contrast, Garudtal remains sparsely inhabited. Tourism, boating, nearby roads, and other anthropogenic pressures appear to intensify plastic accumulation in more urbanised areas.
Measuring the Risk
Researchers collected 24 samples across the three lakes and filtered them using a 90-micrometre sieve. Pollution levels were assessed using three scientific indicators:
• Contamination Factor (CF): Measures contamination associated with specific polymer types.
• Pollution Load Index (PLI): Provides an overall measure of microplastic pollution across sampling sites.
• Polymer Hazard Index (PHI): Evaluates potential ecological risk based on polymer abundance and toxicity scores.
While the Pollution Load Index suggested a preliminary level of contamination, the Polymer Hazard Index exceeded 1,000 in most samples a threshold indicating severe ecological risk. The elevated PHI values were largely attributed to high concentrations of polyester fibres.
An overwhelming majority of detected microplastics were fibres. These particles are particularly concerning because they are more readily ingested by aquatic organisms compared to other plastic forms.
Synthetic textiles are believed to be a major contributor, as a single wash cycle can release hundreds of thousands of microfibres into wastewater systems. In more remote areas such as Garudtal, additional sources may include tyre and road-wear particles transported into the lake through runoff.
The findings highlight the growing threat of microplastic pollution even in ecologically fragile Himalayan ecosystems. The researchers suggest integrating microplastic monitoring into national environmental frameworks such as the National Mission for Clean Ganga and the National Plan for Plastic Waste Management to strengthen mitigation strategies in the region.
As urban expansion and tourism continue to increase across the Himalayan belt, the study serves as a reminder that even remote, high-altitude lakes are not insulated from global plastic pollution. Without sustained monitoring and targeted intervention, these pristine ecosystems could face long-term ecological consequences.