Deputy Commissioner Haripur Waseem Ahmed visited the site with rescue and administrative teams following the incident. He confirmed that water had entered the tunnel but said all local and foreign workers at the site had been evacuated to safety.
According to the deputy commissioner, a Pakistani worker was swept away by the strong water current during the incident but was rescued by emergency teams. No casualties were reported.
An investigation has been launched to determine the cause of the breach. A high-level inquiry committee will examine whether the incident resulted from structural weakness or a technical fault.
Waseem Ahmed said the next course of action would be decided after the inquiry report is received.
Meanwhile, the Water and Power Development Authority (WAPDA) has rejected reports claiming that Tunnel No. 5 had collapsed.
In a statement, WAPDA clarified that a weak section of rock collapsed during excavation of the second bench of the connecting tunnel, allowing water to enter the tunnel and power house area.
The authority said the tunnel itself had not collapsed and described reports suggesting otherwise as baseless.
According to WAPDA, water has been completely drained from the intake pit, while efforts to remove water from the under-construction power house are continuing. The authority added that further water entry into the construction areas had been stopped.
WAPDA also said the incident had not damaged the project's main tunnel, under-construction power house, tailrace culvert or switchyard.
Senior WAPDA officials, project consultants and contractors are present at the site to assess the situation, review safety measures and determine the next steps.
The Tarbela Fifth Extension Hydropower Project is being developed on Tunnel No. 5 of Tarbela Dam. It is designed to add 1,530 megawatts of electricity generation capacity through three units, each with a capacity of 510MW.
The project has an approved cost of $807 million. In May 2021, WAPDA awarded a $354.6 million civil works contract to Power Construction Corporation of China Limited.
The World Bank has provided $390 million in financing, while the Asian Infrastructure Investment Bank has contributed $300 million.
Once completed, the project is expected to generate an average of 1.347 billion units of electricity annually, increasing Tarbela Dam's total generation capacity from 4,888MW to 6,418MW.
The project has already faced several delays, with its completion deadline extended to September 2027.
In September 2024, a Senate standing committee was informed that difficulties in obtaining a no-objection certificate from the Indus River System Authority (IRSA) for closing Tunnel No. 5 were among the major reasons for the delay. Construction was also temporarily suspended in August 2025 due to rising water levels in the dam.
