Microplastics in Nepal's Tilicho Lake (2026): What Trekkers Should Know
A Tribhuvan University study found an average of 42 microplastic particles per litre in Tilicho Lake at 4,917m — and trekkers' synthetic gear and plastic bottles are the source.
One of Nepal's most photographed high-altitude lakes is not as pristine as the postcards suggest. A new study has found microplastics throughout the turquoise water of Tilicho Lake, at 4,917m on the Annapurna Circuit — and the trail of evidence leads straight back to us, the trekkers.
Key facts
- Tilicho Lake sits at 4,917m in Manang, inside the Annapurna Conservation Area.
- Researchers found an average of 42 microplastic particles per litre of surface water.
- Samples came from 6 accessible shoreline sites — the busiest stretches were the dirtiest.
- The dominant plastics — polyester, polyethylene and polypropylene — match trekking gear.
- The work, from Tribhuvan University, was published in the journal iScience.
The study, led by Sahil Shrestha of Tribhuvan University's Institute of Engineering (Pulchowk Campus), is the first quantitative look at microplastics in Tilicho's surface water. Across six nearshore locations the team measured an average of 42 ± 18 particles per litre — a striking figure for a snow-fed lake more than three vertical kilometres above the nearest town. Crucially, contamination was highest exactly where day-trippers and trekkers can walk to the water's edge, and lowest on the harder-to-reach shores.
The particle types tell the story. The researchers logged fibres, fragments, films and foam, dominated by polyester, polyethylene and polypropylene — the same polymers woven into fleece jackets, down layers, tents, rope, dry bags and single-use bottles. Every time a synthetic layer is worn, washed or snagged it sheds fibres; every crushed bottle and torn noodle wrapper adds more. At altitude, cold water and thin biological activity mean those fragments break down painfully slowly.
How bad is 42 particles per litre? For perspective, an earlier 2022 survey of streams and rivers on the Everest Base Camp trail, sampled between 2,600m and 5,000m, averaged around 2 particles per litre. A separate 2026 study of the Gokyo lakes (4,680–5,000m) in the Everest region also flagged rising fibre and fragment loads. Tilicho's higher reading reflects a still lake that traps and concentrates whatever washes in — plus the sheer volume of visitors funnelling to a single, iconic shoreline.
What this means for trekkers
What this means for you
You don't have to cancel the trek — you have to trek cleaner. Carry a reusable bottle and treat lake or stream water with a filter, UV pen or tablets rather than buying stacked plastic bottles; the study's own author calls for ACAP to restrict plastic bottles and polythene bags outright. Wash synthetic layers before you fly in, pack out every wrapper, and resist the urge to rinse gear or swim at the lakeshore. Small habits, multiplied across thousands of boots, are exactly what tipped Tilicho over.
Tilicho remains one of the great days in Nepalese trekking — a punchy side-trip off the Annapurna Circuit to the highest large lake most travellers will ever see. Going with an operator that runs a genuine leave-no-trace policy is now part of protecting it. If the lake is on your list, our Tilicho Lake trek and the longer Annapurna Circuit with Tilicho Lake both build in filtered water, proper waste-out logistics and careful acclimatisation, so you see the turquoise at its best while leaving as little behind as possible.
Sources: iScience / Cell Press (Shrestha et al., Tilicho Lake microplastics); ZME Science; Eos (AGU); ScienceDirect. Figures as reported July 2026.
Cover photo: Arjay Neyra via Pexels (Pexels License).
Source: ZME Science
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