Race against time to find workers missing in Nepal’s hydropower tunnels. Here’s what we know

Nepal’s Flood-Buried Hydropower Tunnels: A Rescue Race Measured in Meters

Goldlaner.com – Deep beneath the Himalayan foothills, workers who were inside reinforced concrete tunnels when a wall of floodwater struck last week may still be alive — but reaching them is proving extraordinarily difficult. Thick layers of mud and sludge have sealed the entrances to multiple hydropower facilities along the Trishuli river, and rescue teams from Nepal, India, and China are working around the clock under worsening weather to bore, drill, and rappel their way toward scores of trapped laborers.

Nepal’s disaster management agency has confirmed that at least 933 workers remain unaccounted for across several hydropower installations situated in remote, mountainous districts through which the Trishuli flows. The exact number of individuals who were inside the tunnels at the moment the floodwaters arrived is unknown, and equally uncertain is how many of them are still breathing. Compounding the urgency, critical access routes — roads, bridges, and landing zones — have been washed out or buried, slowing every phase of the operation.

Scale of the damage

A tally compiled Saturday by the Independent Power Producers’ Association (IPPAN) placed roughly 900 missing workers at 11 separate hydro projects hit by the flooding. Arnold Dix, an Australian geologist who has been advising on-site rescue crews, estimates that as many as 27 hydropower plants sustained damage in the event, with approximately 12 rendered essentially inoperable. Each facility presents a distinct geometric and structural puzzle for rescuers attempting to identify the safest ingress route.

Many of the affected plants feature internal tunnels stretching several kilometers from the surface portal to the underground powerhouse. Workers positioned deep inside could be hundreds of meters from any accessible opening. On the other hand, the tunnels contain rooms stocked with food, water, and basic supplies — resources that could, in theory, sustain trapped individuals for days or even weeks. Oxygen availability, however, remains the critical variable no one can yet verify from outside.

Trishuli 3A: Digging Toward the Unknown

At the Trishuli 3A hydropower plant, where 42 workers were listed as missing, a major boring operation is under way to penetrate the tunnel ceiling so that search teams can descend. The passage connecting the surface to the underground powerhouse — where dozens of personnel were on shift when the flood struck — extends more than four kilometers (2.5 miles) into the hillside.

How much of that length has been inundated with mud or standing water is not yet established, according to Dix.

“So, we might only have to dig 10 meters, or we might have to dig 100 meters.”

Beyond the simple question of distance, additional hazards loom. If the plant’s emergency shutdown systems failed during the flood, the turbine room itself may have filled with water, potentially drowning anyone still inside. Moreover, the act of drilling through the overburden could release that stored water suddenly, endangering the very crews attempting the rescue.

Rescuers at Trishuli 3A have already managed to create an opening large enough to rappel down using ropes and harnesses. When they called out into the darkness, no answer came. In earlier phases of the operation, teams pumped fresh air into the tunnel and pushed food supplies through the breach. Officials said the next step is to send trained rescuers inside carrying oxygen tanks, medical kits, two-way communication gear, and cameras.

Breaking through the reinforced structure above the turbine room, however, introduces its own engineering obstacles.

“We need special equipment to get through the steel and everything that’s surrounding the turbine room. So, it’s layer upon layer of technical difficulties,”

Dix explained.

Chilime: A Shorter Tunnel, No Shorter Nightmare

At the Chilime Hydropower Plant, six workers are believed to be trapped. Jenjen Lama, a mountain guide participating in the search-and-rescue effort, described the facility’s layout: a 250-meter (820-foot) tunnel descending the hillside before connecting to a larger complex housing a service bay, control room, and the main hydropower transformer.

On Sunday, teams entered the tunnel only to find it

“completely blocked by deep, muddy sediment and sludge,”

with the deposit reaching up to their chests. They advanced just 130 meters before conditions forced them to halt. Lama noted that damaged infrastructure in the area also prevents helicopters from landing nearby, limiting aerial support.

“There is the kitchen, there is some food … but I don’t know about the oxygen,”

he said, underscoring the central uncertainty facing every trapped-worker scenario.

International Muscle and Technology

Nepal’s own military and police search-and-rescue units have been reinforced over the weekend by specialists dispatched from India and China — the two superpower neighbors that have poured billions into Himalayan hydropower development over the past decade. Teams deployed thermal-imaging cameras mounted on drones to scan for heat signatures of survivors, while simultaneously locating tunnel entrances and clearing accumulated mud. In parallel, crews drilled vertical holes through the heavily fortified tunnel roofs to create access points and ventilation shafts.

As of Monday, at least 279 hydropower workers had either been extracted by rescue teams or managed to trudge their own way out through the mud- and silt-choked passages. Each survivor carries a harrowing account of hours or days spent in darkness, cold, and uncertainty.

Why Nepal Bet So Much on the Rivers

The disaster lands in the middle of an ambitious national energy strategy. Nepal’s terrain — steep gradients, monsoon-fed rivers, and vast untapped headroom — makes it one of the world’s most promising hydropower frontiers. Both China and India have invested heavily in projects across the Himalayan corridor, betting that the country’s raging waterways can supply electricity for domestic consumption and export. That investment has brought thousands of construction and operations workers into remote valleys where weather windows are short, evacuation routes are few, and the consequences of a single catastrophic flood event can be measured in hundreds of lives.

The Trishuli basin, where most of the missing workers were employed, exemplifies the tension: the very geography that makes the rivers energetically valuable also makes the sites logistically isolated and structurally vulnerable to flash flooding. As rescue operations continue under deteriorating conditions, the question facing Nepal and its neighbors is no longer only how many workers can be pulled out alive, but how the next decade of Himalayan energy development will be engineered to withstand the next flood.