The Nepal government announced it had finished draining the Imja glacier lake in the Everest region on November 23.

The lake was in danger of flooding villages, bridges and trekking trails downstream.

Imja is one of the biggest glacier lakes in the Everest region of the Nepal Himalayas at 5,010 meters above sea level. Since 1960, the small lake has increased to 1.28 square kilometres and 150 metres deep.

The Imja lake is one of six highly dangerous glacial lakes in Nepal.

It took more than six months for about 150 people, including 40 military personnel and Sherpas, to construct an outlet and release almost four million cubic metres of water. The water level of the lake – originally 149 metres deep – fell by 3.4 metres.

The outlet channel built by the Nepal Army on the Imja lake.

Nepal has thousands of glacier lakes. Many of these are filling up fast because of warming temperatures and melting glaciers.

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Glacier lakes have burst their banks 24 times in Nepal since the 1960s, three of which were in the Dhud Koshi river basin in the Everest region.

The Nepal government has set up a flood risk reduction project, supported by the Global Environment Facility and United Nations Development Programme. Early warning systems have been installed in six settlements on the Everest trekking trails to send flood warnings to people downstream.

Nang Thume Sherpa, a member of the glacier lake task force, shows an early warning system installed in Fakding village, Solukhumbu. It will send automated messages from a sensor installed in the Imja lake.

Tourists have suggested that the government shift trails on the Everest to higher places so trekkers and porters climbing the mountain are safe from potential glacier lake floods.

Namche Bazaar, the gateway to the Everest, in Nepal's Solukhumbu district.
Ajit Rai and his wife Ranjita Rai work as labourers in Dengboche village between Imja glacier and the Everest Base Camp. “Last year, a small flash flood started from Lotse glacier and mixed with the Imja river. Although it only destroyed one bridge near Dengboche, it made me think more about the safety of my family,” said Ajit Rai.
Kalma Lama, from Lukla town, runs a shop in Dengboche. She is happy the lake has been drained. She also experienced the flood from the Lotse glacier lake last summer. “Although there was no loss from the flood, the Imja river is terrifying,” she said.
Schoolchildren cross a suspension bridge over the Dhud Koshi river near Fakding village, where the early warning system has been installed.
Smoke billows from a hotel chimney in Debuche as the sun sets over Mount Everest. Recent studies have shown that black carbon from such smoke is causing faster retreat of glaciers in the Himalayan region.
Night view of the Imja river valley from Chukum, Solukhumbu district, Nepal.

This article first appeared on The Third Pole.