Nepal Is Going to Drain Four Glacial Lakes After the Deadly Floods, Here's Which Trekking Valleys They Sit Above

Nepal will start work this fiscal year on draining four high-risk glacial lakes, Thulagi, Lower Barun, Lumding Tsho and Hongu II, in a roughly US$50 million project that could take up to six years, Reuters reported on 2 October 2026. It follows the August flood that killed more than 1,400 people. For trekkers the practical answer today is that nothing is closing, and the work is a long-term safety programme, not an emergency.

What Nepal has actually announced

Design work and detailed studies for the four lakes begin in the fiscal year that runs until mid-July 2027. The draining itself will use gated structures that release water in a controlled way into nearby rivers, and it starts only after those studies. The money comes from the Green Climate Fund, the UN Development Programme and the Nepali government.

The project also covers sensors, a flood forecasting and warning system, and preparing downstream communities. Subash Tuladhar, an expert at the government research centre overseeing it, said the aim is to lower the risk of the lakes breaching their natural dams and to reduce downstream flood risk. The lakes sit between roughly 4,050 and 5,483 metres.

Has Nepal drained a lake like this before

Yes, twice. Reuters notes that Nepal lowered Tsho Rolpa by 3 metres in 2000 and Imja Lake, near Everest, about ten years ago. So the engineering is known, but the new lakes are higher and harder to reach, which is why the timeline runs to six years.

Glacial lake outburst floods are not rare here. Reporting on the project puts the record at around 26 such events over four decades. We explain the mechanism in our guide to glacial lake outburst floods in Nepal, and the monitoring side in Nepal's GLOF early warning systems.

Does this change your trek this autumn

No. The studies have not started, so there is no construction, no closure and no new permit rule attached to the announcement. The August disaster remains the context: the toll is still rising and thousands were reported missing, as we covered in one month after the floods. Routes touching the flooded Rasuwa corridor are a separate question from the lakes announced today.

If you are walking the Makalu or Khumbu valleys, the useful habit is simple: ask your operator where the nearest warning system is, camp away from the lowest riverbank, and never treat a quiet river as proof a valley is safe.

Which of our treks pass near these valleys

The Makalu Barun valley is the home of our 18-day Makalu Base Camp trek, and the Dudh Koshi basin feeds the route of our 12-day Everest Base Camp trek. The Manaslu side is covered by our 14-day Manaslu Circuit. Prices are on each page, with the solo rate shown first.

Cover photo: Ashok Sharma via Pexels (Pexels License). Section photos: jerry Shi via Pexels (Pexels licence); Subash Thapa via Pexels (Pexels licence); Roshan Rai via Pexels (Pexels licence); Quang Nguyen Vinh via Pexels (Pexels licence); Abdul Kayum via Pexels (Pexels licence).