Lake Sarez (3,263m) is often referred to as the ‘sleeping dragon’, and it is easy to see why. It was formed by an earthquake in February 1911 estimated to be between 6.5 and 7.0 on the Richter scale, as the resulting landslide shifted over 2 billion m³ of rock and formed the Usoi Dam. At approximately 5km long, 3.2km wide and up to 567m high, it is the tallest natural dam in the world.
Named after the village buried by the landslide, it killed an estimated 302 people. The isolation and destruction of the mountain tracks was such that word did not reach the Russian posts at Murgob and Khorog about the earthquake for six weeks.
Following a landslide that caused a 2m-high wave in the lake in 1968, investigations were held into the stability of the dam. The primary danger is thought to be a partially detached section of rock around 3km³ in size which could break loose and fall into the lake. Owing to the narrowness of the valley below, a flood would be highly destructive.
Initially, a 50m-tall wave of water travelling at 300km/h would destroy all of the villages in the Bartang Valley. Within 10 hours, the wall of water would flood the flat parts of south Tajikistan before dividing into two large rivers which move on to Uzbekistan and Turkmenistan, finally reaching the Aral Sea. In total, it is thought the flood could affect over 5 million people, 370,000 of whom are from Tajikistan.
Treks focused on Lake Sarez start in Barchidev, the last settlement where you’ll find a homestay. The first day of the trek takes you south along the Murgob River and to the vast, natural dam at Usoi, the village now buried beneath the rockfall. It is possible to turn from here to Barchidev if you only have time for a short trek, though most people prefer to continue round the lake to Irkht. There are two variations to this part of the route: a boat trip across the water, or the strenuous and vertigo-inducing climb over the Marjanai Pass (3,972m).
Irkht was once a meteorological station, but little indication of this now remains. It’s another day’s hard walk up the Langar River to Vykhinch and thence the three head-like lakes at Uchkul. There is another steep climb, this time to the Langar–Kutal Pass (4,630m), from where it is 20km to the summer pastures at Langar (not to be confused with Langar in the Wakhan Corridor). You’ll be welcomed with bread and tea, and possibly fresh ewes’ milk too.
Langar lies just below Jasilkul, one of the four largest lakes in the Pamirs. The final leg of the trek winds its way down the river valley to Bachchor at the northeastern end of the Gunt Valley. The path rejoins the road at Bachchor, whence it is 22km back to the Pamir Highway or 116km to Khorog. We would advise driving.
To complete this trek you will need detailed topographical maps of the area. The best currently available ones are those produced by the Soviet military, and thankfully the topography of the area has changed little since they were drawn up. You can download the complete set from Mapstor. They go down to 1:50,000 scale.
Maps are no substitute for a competent guide who knows the local area and can read the conditions on the mountains. You should contact PECTA or Pamir Silk Travel, both of which are in Khorog, to get a reliable recommendation.