Rivers and lakes · Chhukung
See Imja Tsho, the lake they lowered
Walk from Chhukung to a moraine viewpoint over Imja Tsho, a glacial lake that grew from meltwater ponds in the 1960s into one of the Everest region's largest. In 2016 engineers lowered it by about 3.4 m to protect villages downstream.
Imja Tsho barely existed in the early 1960s, when aerial photos show only small ponds on the Imja glacier. As the glacier thinned and retreated, the ponds merged into a lake held behind a wall of loose moraine. By the 2000s it was one of the fastest-growing glacial lakes in the Himalaya, and scientists warned that a breach could send a flood down the Imja valley past Chhukung, Dingboche and on towards Pangboche.
In 2016 the Nepal Army, with the government and international partners, built an outlet channel with gates through the moraine and lowered the lake by about 3.4 m, reducing the volume of water that could burst out. It was one of the first such projects in Nepal. Thame's 2024 flood, in a different valley, showed how real the danger is.
The walk follows the trail towards Island Peak base camp, branching onto the moraine for the view of the lake's grey-green water and the ice cliffs at its head. Give yourself 4–5 hours return. It is a sobering, beautiful sight. Stay on the established paths, as moraine is unstable, and do not approach the outlet works.
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Questions
Why was Imja Tsho lowered?
The lake grew rapidly as the Imja glacier melted, held back only by unstable moraine. A breach could have caused a glacial-lake outburst flood down the Imja valley. In 2016 the Nepal Army and partners built an outlet channel and lowered the water by about 3.4 m, reducing the flood risk to Dingboche and villages below.
Can I see Imja Tsho from Chhukung?
Not from the village itself. You need to walk towards Island Peak base camp and climb onto the moraine, about 2 hours from Chhukung, or climb Chhukung Ri, from whose summit the lake is clearly visible to the east. Both make good acclimatisation outings.
Is Imja Tsho dangerous to visit?
The viewpoints on the moraine are safe if you keep to established paths and stay away from the outlet works and steep moraine edges, which can collapse. The flood risk has been reduced by the 2016 lowering. Follow your guide's advice and avoid the area in bad weather or after heavy snow.
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