Laya Road Closure After Sintaphu GLOF: Trekker Update

By Best of Bhutan Research Desk · November 4, 2026 · 8 min read

Update, 5 November 2026: The artificial lake that formed behind flood debris at Taktsemakhang is reported stable, with no rise in water level and a constant outflow, according to The Bhutanese. Prime Minister Tshering Tobgay inspected the site and said it was not very dangerous. The Gasa administration plans to drain it with an excavator, and controlled blasting is being considered, but work is held up because the Punakha–Gasa road is cut and no fuel can reach the site. The NCHM ground assessment of the Sintaphu lakes themselves has not been reported yet, and no reopening date has been given for the Laya road. Details are in the artificial lake section below.

The Laya road closure caused by the Sintaphu glacial lake outburst is worse than first reported. On 2 November 2026, Kuensel reported that floods had blocked three major sections of the Laya Gewog Centre road between Koina and Tongchudra, and that the Tongchudra bridge had been washed away completely. The same day, BBS reported that satellite analysis suggests the flood began with an outburst from an upper lake above Sintaphu, and that a substantial volume of water is still held there.

This post is an update to our Sintaphu GLOF 3D flood model, published on 30 October, the day after the outburst. That post covers the flood itself, Gasa Tsachu and the Punakha–Gasa highway. This one covers what has been reported since, and what it means if you are planning a trek in Gasa.

Key Facts at a Glance

DetailWhat has been reported
EventGlacial lake outburst flood (GLOF) from Sintaphu (Shintaphu) Tsho, Laya Gewog, Gasa
Tongchudra bridgeWashed away completely
Human casualtiesNone reported
Date of outburstEvening of Thursday 29 October 2026
Likely triggerOutburst from the upper of the two Sintaphu lakes, based on satellite data (preliminary)
Water lostLower lake about 80% of its volume; upper lake about 10% (ICIMOD specialist, via BBS)
Laya roadThree major sections blocked between Koina and Tongchudra
LivestockAt least 128 yaks and 12 horses suspected dead; preliminary loss Nu 6.8 million (Department of Livestock, via Kuensel)
Gasa TsachuHot spring facilities washed away on 29 October
Artificial lake (Taktsemakhang)Stable, no rise in water level, constant outflow; monitored on site; drainage planned but stalled for lack of fuel (The Bhutanese)
Ground assessmentNCHM team waiting for a helicopter; findings so far are from remote sensing
Reported byBBS and Kuensel, 2 November 2026; Kuensel, 4 November 2026; The Bhutanese, early November 2026

What Changed Since the First Reports

The upper lake probably started it

Sintaphu is not one lake but two. According to BBS, the National Centre for Hydrology and Meteorology (NCHM) says the lower lake holds more water. BBS put the two lakes together at roughly 3,200 Olympic swimming pools of water, and said the flood released close to 2,000 of them, about 60% of the combined volume.

BBS quoted Dr Sonam Wangchuk, a cryosphere specialist at the International Centre for Integrated Mountain Development (ICIMOD), on the satellite analysis. His estimate is that the lower lake lost about 80% of its volume and the upper lake about 10%. That points to a chain reaction: the upper lake burst first and pushed water into the lower lake, which then failed. Kuensel reported the same preliminary finding on 4 November.

Early reports on 30 October said the cause had not been confirmed (Climate Fact Checks). The upper-lake explanation is still preliminary. It has not been checked on the ground.

Water is still held in the upper lake

The upper lake lost only a small share of its water. BBS reported that a substantial volume remains in it. Sintaphu is one of the 17 glacial lakes Bhutan classes as potentially dangerous, so the authorities will want to see it in person before calling the area safe.

The artificial lake at Taktsemakhang is stable for now

After the outburst, a lake formed behind flood debris at the confluence of the Shintaphu Chhu and Lungu Chhu at Taktsemakhang (BBS spells it Taktsi Makhang). On 30 October NCHM issued an advisory about it.

The latest report, from The Bhutanese, says:

Stable is not the same as safe. The lake is still held by loose debris, and the authorities have not said when it will be drained. In our earlier post we modelled what a breach of a debris dam at this point could do downstream.

The ground team has not reached the site yet

NCHM Director General Karma Dupchu told BBS the agency was "waiting for helicopter availability" to send a post-flood assessment team. Everything known so far about the lakes comes from satellite images. Communities along the Mo Chhu have been asked to stay alert. As of 5 November we have not found a published report of the ground assessment.

The Laya Road and the Tongchudra Bridge

The first wire reports, carried by Al Jazeera from Reuters on 30 October, said part of the road to Laya was impassable and cited Kuensel saying it was closed to traffic indefinitely.

Kuensel's 2 November report gives more detail:

Kuensel did not give a date for reopening the road or replacing the bridge in the part of the report we could access. We have not found an official repair timeline. Treat the road as closed until the Gasa Dzongkhag administration or the Department of Surface Transport says otherwise.

The Punakha–Gasa highway was also damaged. On 30 October a section near km 31.85 was reported lost and the road closed until further notice (Climate Fact Checks). We have not seen a reopening announcement.

Laya's Herders Lost at Least 128 Yaks

Laya is a highland community that depends on yaks. On 2 November, Kuensel reported that at least 128 yaks and 12 horses are suspected to have died in the flood. The Department of Livestock put preliminary losses at Nu 6.8 million.

No people were hurt; the area was evacuated before the water arrived (Climate Fact Checks). But for the herding families, the loss of animals is a serious economic blow. Kuensel's 4 November feature on climate and biodiversity also noted damage to farmland and infrastructure.

For background on how herding works in the north, see our post on National Yak Day and Bhutan's herders.

Sentinel-2 satellite images from 25 October 2026, four days before the outburst. Left: Sintaphu Tsho at the head of the Mo Chhu valley. Right: the river confluence below Laya where a debris-dammed lake was later reported

Before the outburst, 25 October 2026. Contains modified Copernicus Sentinel data 2026.

What This Means for Travellers

Laya trek

The Laya trek depends on the road from Gasa and on the trails and bridges in the Mo Chhu valley. With three road sections blocked, a key bridge gone and the flood channel not yet assessed on the ground, do not assume a Laya departure will run as planned this season.

If you are booked:

Snowman trek

The Snowman trek passes through Laya on many itineraries. The same questions apply. It is also the hardest trek in Bhutan, and any extra days lost to detours add to the altitude risk. Our complete trekking guide covers seasons, permits and acclimatisation.

Gasa Tsachu hot springs

The Gasa Tsachu facilities were washed away on 29 October (Al Jazeera/Reuters). They were also hit by a flash flood in 2021. There is no reopening date. Do not plan a visit until the Gasa Dzongkhag administration reopens the site.

Punakha and the Mo Chhu valley

After the outburst, Punakha Dzong was closed to the public as a precaution, and residents of the Mo Chhu and Punatsangchhu valleys were told to avoid the riverbanks (Al Jazeera/Reuters). Downstream, the Punatsangchhu-II hydropower project shut its generating units and opened its dam gates as a precaution on the night of the flood (Eastern Lens). Wangdue Dzongkhag has asked people not to collect or eat dead or stranded fish from the river (The Bhutanese). We have not confirmed whether the dzong has reopened. Ask your guide before you go, and stay away from the riverbanks until NCHM lifts its advice. See our Punakha guide and our Bhutan travel restrictions guide for other closures.

If you want a high trek this season instead

Treks in the Paro and Thimphu valleys are outside the Mo Chhu flood path. The Druk Path trek between Paro and Thimphu and the Jomolhari base camp trek are the usual alternatives. Check current trail conditions with your operator before switching.

How to Check the Latest Status

Frequently Asked Questions

Is the Laya road open?

No. As of 2 November 2026, Kuensel reported three major sections blocked between Koina and Tongchudra and the Tongchudra bridge washed away. No reopening date has been announced.

Can I still do the Laya trek in 2026?

It depends on the route your operator uses and how fast the road and bridge are repaired. Until the authorities confirm access and the post-flood assessment is done, ask your operator for a written plan and an alternative such as the Druk Path or Jomolhari trek.

What caused the Sintaphu GLOF?

Preliminary satellite analysis reported by BBS and Kuensel suggests an outburst from the upper of the two Sintaphu lakes pushed water into the lower lake, which then released most of its volume. This has not yet been verified on the ground.

Is there still a flood risk in Gasa and Punakha?

Officials have not said the danger is over. A substantial volume of water remains in the upper Sintaphu lake. The artificial lake at Taktsemakhang is reported stable with a constant outflow, but it has not been drained yet. Communities along the Mo Chhu and Punatsangchhu were asked to stay alert and avoid riverbanks. Follow NCHM warnings.

Is Gasa Tsachu hot spring open?

No. The facilities were washed away on 29 October 2026. Check with the Gasa Dzongkhag administration before planning a visit.

Related Reading

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