Sarez Lake

On 18 February 1911, an earthquake of around magnitude 7.4, with estimates ranging from 7.0 to 7.7, struck the central Pamirs late at night. The shaking triggered one of the largest landslides in recorded history, sending roughly two cubic kilometers of rock nearly 1,800 meters down into the Murghab River valley. The village of Usoi was buried whole beneath billions of tons of debris. An estimated 90 to 302 people died, and the region was so remote that word took six weeks to reach the Russian posts at Murghab and Khorog.

The rockslide sealed the Murghab River completely, and water began rising fast behind the new barrier. The village of Sarez, which gives the lake its name, was submerged within months. The lake rose by around 75 meters a year at first and had largely stabilized by the mid-1920s, as seepage through the base of the dam came to balance the inflow. Today Sarez stretches sixty kilometers through a narrow valley, holding seventeen cubic kilometers of water at 3,263 meters in one of the most seismically active corners of Central Asia.

The Usoi Dam stands 567 meters tall, with a volume of roughly two cubic kilometers of rock and a barrier that spans about three kilometers across the valley floor. USGS, UNESCO and the World Bank record it as the highest dam in the world, natural or engineered, well over twice the height of the tallest dams ever built. Water never flows over the top. It seeps through the base and emerges as a line of large springs on the downstream face that reform the Murghab, which becomes the Bartang River. The freeboard between the lake surface and the lowest point of the crest sits at around 50 meters.

The main hazard comes from an unstable slope on the lake's right bank, the northern shore, estimated at anywhere from 0.5 to 3 cubic kilometers of rock. A rapid collapse into the lake could raise a wave large enough to overtop the dam and send a flood down the Bartang and Panj rivers, reaching communities in Tajikistan, Afghanistan, Uzbekistan and Turkmenistan. World Bank impact studies have put the worst case at up to five million people downstream, though such a total and instant failure is considered unlikely. An early warning system, first built by the World Bank and rebuilt with Asian Development Bank funding around 2021, monitors the dam with GPS, seismic and lake-level instruments and roughly 30 siren towers, operated by Tajikistan's Committee of Emergency Situations.

Sarez is one of the hardest places in Tajikistan to reach, and that is part of why it stays so undisturbed. No road touches the water. Most expeditions drive two days from Dushanbe over the Shurobod Pass into the Bartang Valley, then trek from the roadhead at Barchidev, crossing cable bridges over the Murghab and climbing the final stretch up the face of the Usoi Dam itself. The lake opens only to travelers carrying a GBAO permit and a separate Sarez permit, with a local guide required throughout. It is a true expedition rather than a sightseeing stop, and the effort is the point. Days of walking earn a shoreline that only a handful of people reach each year.

The route is also a journey through Pamiri country. The Bartang villages are home to Ismaili families who follow the Aga Khan and welcome travelers into the traditional five-pillared house, the chid, whose design carries meaning more than two thousand years old. Meals of shirchoi and qurutob are shared beneath a skylight built to frame the four elements, and Pamiri hospitality along the valley is unhurried and generous. Reaching Sarez means moving slowly through this landscape and seeing a corner of the Pamirs that very few travelers ever will.