Largest & Highest Glacial Lakes of Nepal: Rankings

The lake most often named as the largest glacial lake in Nepal is Tsho Rolpa, in the Rolwaling valley of Dolakha district, about 115 km northeast of Kathmandu. It covers roughly 1.54 square kilometres (some sources round this to 1.6 km2), sits at an elevation of about 4,550 metres above sea level, and is around 3.45 km long. With a maximum depth near 135 metres and an estimated 85 to 86 million cubic metres of water held back by a loose end-moraine dam, it is also one of the most closely monitored glacial lakes in the Himalaya.

The answer to "biggest glacial lake in Nepal" is not entirely clean, however, because it depends on which lakes you count. Lower Barun, in the Makalu Barun National Park of Sankhuwasabha, is the deepest known glacial lake in the Nepal Himalaya at about 205 metres, holds a larger volume (roughly 112 million cubic metres), and recent surveys put its area in the same 1.5 to 1.8 km2 range as Tsho Rolpa. Tilicho Lake in Manang is larger still by surface area, at about 4.8 km2, but it is an older bedrock-and-moraine basin rather than a lake newly formed by 20th and 21st century glacier retreat.

In short, among the recently formed, moraine-dammed proglacial lakes tracked for outburst-flood risk, Tsho Rolpa and Lower Barun sit at the top; if you count every glacier-fed high-mountain lake, Tilicho is the largest by area. This guide ranks all of them and explains the differences so the superlatives make sense.

A glacial lake is a body of water that forms in association with a glacier, most commonly where a retreating glacier leaves a basin dammed by the loose rock and debris (moraine) it once pushed ahead of it. As Himalayan glaciers thin and pull back under a warming climate, meltwater pools behind these unstable dams and the lakes grow, sometimes rapidly. Because the natural dams can fail suddenly, the largest of these lakes are studied for the danger of a glacial lake outburst flood, or GLOF.

The most authoritative recent count comes from the 2020 (2077 BS) inventory prepared by the International Centre for Integrated Mountain Development (ICIMOD) and the United Nations Development Programme (UNDP). It mapped 3,624 glacial lakes larger than 0.003 km2 across the transboundary Koshi, Gandaki and Karnali river basins of Nepal, China's Tibet Autonomous Region and India. Of these, 2,070 lie within Nepal, and 21 were flagged as potentially dangerous glacial lakes (PDGLs) needing close monitoring. Older ICIMOD inventories put Nepal's total closer to 2,323 lakes, so counts shift with imagery and methods.

The ranking below lists Nepal's largest glacial lakes by surface area, with the caveat that figures move year to year as the lakes expand and as new satellite imagery is analysed. Tilicho is listed first because it is genuinely the largest glacier-associated lake by area, but it is set apart because it is an older basin rather than a recently formed moraine-dammed lake. Among the moraine-dammed lakes that matter for outburst-flood planning, Lower Barun and Tsho Rolpa are the two largest, followed closely by Imja.

For the query "highest glacial lake in Nepal," the headline answer is Kajin Sara (also written Kajin Sara / Singar) in Chame rural municipality of Manang district. Discovered and publicised in 2019 (2076 BS) by a local team, it lies near the base of Lamjung Himal at a reported elevation of around 5,000 to 5,200 metres (about 5,020 m is the figure most often cited). It has been promoted as the world's highest lake, roughly 80 metres above Tilicho, though that record has not yet been formally certified and its exact elevation is still being confirmed by survey.

Among the large, well-established lakes, Imja Tsho is the highest at about 5,010 metres, higher than Tilicho at about 4,919 metres. Altitude is a major reason these lakes matter: at such heights they sit directly below steep, ice-clad peaks, so avalanches, rockfalls or ice calving into the lake can trigger a surge over the moraine dam. The list below ranks the highest glacial and high-mountain lakes for which reliable elevations exist.

The fastest-growing glacial lake in Nepal that is most often cited is Imja Tsho, because it has one of the longest measured records. It began as scattered supraglacial ponds in the early 1960s and expanded from about 0.03 km2 in 1962 to roughly 1.3 km2 by the 2010s, an average growth of about 0.026 km2 per year. The lake is fed by the Imja and Lhotse Shar glaciers, whose accelerating retreat above the Everest base-camp trekking route has driven the expansion.

By raw area gained, Lower Barun has grown even faster in recent decades, adding roughly 0.04 km2 per year and enlarging by about a third between 2000 and 2017. Tsho Rolpa continues to creep outward too, with its area rising about 3.3 percent between 2010 and 2015 as the Trakarding (Tarkading) glacier at its head retreats at roughly 60 metres a year. The common thread is glacier retreat: as ice melts back, the moraine basins behind it fill and lengthen.

The reason Nepal keeps such careful rankings of its biggest glacial lakes is the threat of glacial lake outburst floods. A GLOF happens when a moraine or ice dam fails, releasing a wall of water, mud and boulders downstream in minutes. Nepal's most cited disaster is the 1985 (2042 BS) Dig Tsho GLOF in the Khumbu, which destroyed the nearly complete Namche small hydropower plant and swept away bridges and farmland. The ICIMOD/UNDP 2020 inventory flagged 21 potentially dangerous glacial lakes inside Nepal, most of them in the Koshi basin in the east.

Two of the largest lakes have already been actively managed to reduce risk. At Tsho Rolpa, an engineered outlet channel and siphon system lowered the lake by about 3 metres around 2000, paired with an early-warning system downstream. At Imja Tsho, the Nepal Army together with UNDP and the Department of Hydrology and Meteorology cut a controlled outlet in 2016 (2073 BS) and lowered the lake by about 3.4 metres, draining several million cubic metres of water. Thulagi and Lower Barun remain high-priority lakes for study because major Marsyangdi and Arun/Barun-basin settlements and hydropower projects lie downstream.