Lake · Bhutan
Thorthormi Lake
Thorthormi Lake is a young lake at the end of a glacier high in the Himalayas of Bhutan, about 4 415 metres above the sea. It is the largest glacier lake in Bhutan, and it is still growing.
Where is Thorthormi Lake?
Countries on its shores: Bhutan.
Largest lake of: Bhutan.
Middle of the lake: 28.10° N, 90.26° E
The story behind it
About 60 years ago, there was no lake here yet. At the end of the Thorthormi Glacier in the Lunana area, meltwater collected in small ponds on and beside the ice. The glacier melted and pulled back by about 30 to 35 metres a year, and the ponds joined together into one lake. In 2000 it covered about 1 km², and by 2018 about 3 km². Only a wall of loose rock and gravel, called a moraine, separates it from Raphstreng Lake, which lies about 80 metres lower. If this wall broke, a dangerous flood could rush down the valley. So from 2009 to 2011, about 360 workers from Lunana worked by hand with simple tools, at more than 4 400 metres, to let water out. The water level dropped by 3.68 metres. Later, soldiers helped until it had dropped by 5 metres. Thorthormi Lake is the largest glacial lake in Bhutan, and it is growing fast as the glacier above it melts.
Find it on the globe
Thorthormi Lake is there as a small blue dot with its name, right on the water. From far away the planet is only a blue ball; detail arrives as you zoom in, and this one appears once you are close enough. Open it on the globe.
It sits at its real coordinates, not near them — the same numbers listed in the facts above. Switch off the layer for this kind of place and it disappears again; the buttons for that are down the right-hand edge.
Questions children ask
How big is Thorthormi Lake?
In 2018 it covered about 3.05 km²; another measurement gives about 3.4 km². The lake keeps growing because the glacier behind it is melting.
Why do people worry about the lake?
Only a wall of loose rock holds the water back from a lower lake next to it. If the wall broke, a big flood could rush down the valley.
How did people make the lake safer?
From 2009 to 2011, hundreds of workers used their hands and simple tools to let some water out, and later soldiers joined in. Together they lowered the lake by about 5 metres.
Where these numbers come from
Every figure on this page was checked against public reference sources before publication. Where sources genuinely disagree, the text says so.
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