Srisailam dam faces safety issues as plunge pool repairs lag

Despite urgent directives from the National Dam Safety Authority (NDSA) in May to address the plunge pool’s structural threats before the monsoon, the progress is dismal. High water inflows and procedural delays are complicating repair efforts.

Hyderabad: Persistent safety concerns due to unresolved plunge pool issues and newly reported gate leaks in the Srisailam project are raising alarm among project officials and irrigation experts from both the Telugu States.

Despite urgent directives from the National Dam Safety Authority (NDSA) in May to address the plunge pool’s structural threats before the monsoon, the progress is dismal. High water inflows and procedural delays are complicating repair efforts.

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The plunge pool, a critical depression downstream of the dam, has been eroding since the devastating 2009 floods, which created a massive crater threatening the dam’s foundation.

The NDSA’s May 2025 inspection revealed deep scour zones up to 5 metres below the original bed level, particularly between spillway blocks 9 to 13 and severe damage to protective steel cylinders. It wanted immediate short-term measures, including geophysical surveys and cylinder restoration, to be completed by May 31, but as of July 6, these tasks remain incomplete.

An underwater survey by Sea Lion Offshore Diving Pvt Ltd. concluded on June 26, documented spots of serious erosion and voids. The final report is due by July 15.

Andhra Pradesh Chief Minister N Chandrababu Naidu ordered immediate repairs on June 7, with proposed World Bank funding, but no clear timeline has emerged, drawing criticism for administrative delays.

Adding to the crisis, on July 5, leaks were reported from three of the dam’s 12 radial crest gates, with Gate No. 10 experiencing the severe leakage. But officials, who sought anonymity, ruled out any potential link between the leakage and the plunge pool’s structural issues.

The dam is receiving heavy inflows of 1,34,790 cusecs. An outflow of 67,399 cusecs was being maintained by the project with its present storage standing at 180.67 TMC, nearing its 215.81 TMC capacity.

The high water levels, driven by upstream flooding from the Tungabhadra and Jurala projects, are complicating repair efforts, as monsoon conditions make on-site work challenging.

Telangana officials have already warned of catastrophic downstream impacts, including risks to the Nagarjuna Sagar and Pulichintala dams and Vijayawada, should the dam fail because of the plunge pool issues.

By 2012, a void measuring 46.65 metres deep, 400 metres wide, and 270 metres long had formed, with its edge perilously close to the spillway.

On September 3, 2012, then Minister of State for Water Resources, Vincent Pala, replied to a question in Rajya Sabha, stating that ‘underwater inspection and videography of the plunge pool area revealed rock-cut terraces, cavities and pits’.

NDSA inspections in 2024 revealed the void’s depth had worsened to 143 feet, with deep scour zones near Gates 7 to 10 threatening retrogression toward the dam’s foundation, risking catastrophic failure.

NDSA Chairman Anil Jain inspected the Srisailam Dam’s plunge pool recently and emphasized the urgent need for repairs due to structural concerns, particularly a large void threatening the dam’s stability. He also wanted an approach road to be laid giving free access to the plunge pool. But the works proposed on Srisailam are all still in the planning stage.