Electricity generation from hydropower projects with combined capacity of 176.1 megawatts along the Trishuli corridor remains uncertain after the Bhotekoshi flood destroyed the 220 kV Trishuli-3B Hub substation in Nuwakot.

Although several plants connected through the Chilime-Trishuli 220 kV transmission system were spared direct damage, they cannot send power to the national grid because the substation through which their electricity was evacuated has been destroyed.

The affected plants include the 78 MW Salasungi (Sanjen), 14.8 MW Upper Sanjen, 42.5 MW Sanjen, 14.8 MW Upper Mailung and 5 MW Mailung Khola projects, with combined capacity of 155.1 MW. Three projects in Nuwakot’s Tadi Khola corridor, with a combined 21 MW capacity, are also unable to transmit power.

The flooding halted a total of 256 MW from operational plants across the region. Due to transmission and substation infrastructure damage, 176.1 MW cannot be evacuated to the national grid. Infrastructure failure forced several plants to operate in isolated mode, supplying power strictly to nearby local settlements rather than national lines.

The shutdown creates critical hurdles for managing energy demand in the Kathmandu Valley, where these plants serve as vital load sources, especially during the dry winter period.

Dirghayu Kumar Shrestha, acting managing director of the Nepal Electricity Authority said that the output disruption will exacerbate winter grid management. “When projects closed following the floods, power could not be evacuated to the national system, while some projects were wiped out entirely,” said Shrestha. “During the dry season, even half their capacity helps maintain supply. Our priority is to reconnect undamaged plants as quickly as possible.”

Shrestha added that despite surviving the flood intact, the installations cannot operate without operational transmission lines and hub infrastructure. “Electricity arriving at the Trishuli-3B Hub cannot be evacuated. Reconnecting these projects to the national grid is our focus, and we are working on a plan to restore connectivity within six months.”

To restore grid connectivity, the NEA has assigned NEA Engineering Company to evaluate alternative transmission options. The company is currently carrying out a feasibility study for a direct line from the 220 kV Chilime Hub Substation to the 220 kV Matatirtha Substation.

If constructed, this route would bypass the destroyed Trishuli-3B Hub Substation completely. Chirantan Rana, chief executive officer of NEA Engineering Company, explained that plans involve running the Trishuli–Kathmandu 220 kV double circuit transmission line with one circuit operating at 220 kV and the second at 132 kV.

According to Rana, preliminary assessments indicate that 22 pylons along the 220 kV route from Trishuli-3B Hub to Matatirtha sustained damage. “Pylons between Trishuli-3B Hub and Chilime suffered minimal damage, so preparations focus on connecting Chilime Hub directly to Matatirtha,” he said. “Since Samundratar operates at 132 kV, we plan to charge one circuit at 220 kV and the other at 132 kV.”

Rana said additional damage, including 15 pylons along the 132 kV Samundratar–Trishuli 3B Hub line, 24 along the 66 kV Chilime–Trishuli line, and four along the 66 kV Trishuli–Balaju line. “Because road networks are disrupted, these details reflect a preliminary assessment. We will submit a comprehensive report detailing precise routes and pylon locations.”

Shrestha confirmed the NEA will act on the engineering findings once submitted. “The Trishuli-3B Hub was swept away. Studies are underway to link Chilime Hub directly to Matatirtha, and construction will begin once the restoration report is finalised.”

Located at Pairebesi in Nuwakot’s Kispang Rural Municipality, the 220/132/33 kV Trishuli-3B Hub Substation previously connected to Matatirtha via the Trishuli-Kathmandu line. It received power via a 28 km 220 kV double-circuit line running from the Chilime Hub Substation in Rasuwa’s Amachhodingmo Rural Municipality.