Quickly repair SEA's largest dam

Serious damage to multiple components

After years of construction since 2008, the Thao Long Dam was put into operation as the largest saltwater prevention and freshwater retention dam in Southeast Asia. Located at the river mouth on weak soil, the dam consists of many modern components, including 15 sluice gates that ensure the safe passage of vessels. The project was built by the former Ministry of Agriculture and Rural Development and later handed over to the Hue Irrigation Works Management and Operation One-Member State Company Limited for management and operation.

Although regarded as a large-scale irrigation project, Thao Long Dam was built with a relatively modest investment compared to its size at the time of construction (150 billion VND). For nearly two decades, the dam has yielded positive results in preventing saltwater intrusion, preserving the freshwater resources of the Huong River, and, together with the Ta Trach Reservoir and Binh Dien Hydropower Plant upstream, ensuring sufficient water supply for agriculture, industry, ecological environment, and daily life in the Huong River Delta region.

However, the Thao Long Dam has not been immune to the passage of time. At present, many components have severely deteriorated, and the structure is straining to fulfill its functions, posing risks to both operational efficiency and overall safety.

As observed by reporters on site, the hydraulic system used to open and close the sluice gates has been damaged, while mechanical equipment on the structure has rusted and, in some cases, corroded through. Erosion beneath the pile caps at the base beams has appeared at nearly all sluice gates, with strong seepage flows significantly undermining the dam’s capacity to prevent saltwater intrusion and retain freshwater. Of particular concern is the fact that the dam was not designed with backup sluice gates; thus, if a gate fails (unable to open or close), the consequences could be extremely serious.

In addition, the power station, hydraulic pumps, and pressure-regulating valve clusters of the Thao Long Dam have also degraded, with pumps unable to provide sufficient pressure to operate the gates. At times, some gates cannot be opened or closed to regulate water flow, forcing the operating unit to adopt temporary measures, such as dismantling the hydraulic system from another gate (after adjustment) to replace it creating significant risks and safety hazards.

Ms. Tran Thi T., a local resident living near the Thao Long Dam, said that ever since the dam was put into operation, people have felt secure in agricultural production, no longer worried about saltwater intrusion as before.

"Recently, seeing the structure deteriorating, with damage here and there, everyone has been very anxious and uneasy. If the dam were to experience a failure without timely repairs, the damage would undoubtedly be enormous, affecting the entire area especially the water supply for agricultural cultivation," Ms. T. shared.

In addition to the traffic bridge, the Thao Long Dam system also includes a lock chamber measuring 53 meters in length and 8 meters in width. The dam ensures waterway traffic for vessels of up to 50 tons and a roadway bridge that allows vehicles of up to 13 tons to pass.

Urgent repairs required

The repair of the Thao Long Dam has now become more urgent than ever. Recently, the Ministry of Agriculture and Environment approved an adjustment to the urgent repair project to ensure dam safety, with a total investment of over VND 348 billion from the Central Government budget managed by the Ministry. The project is invested by the Hue City Agricultural and Rural Development Construction Investment Project Management Board and will be implemented over four years. Construction is expected to begin in October 2025.

Specifically, the project will address seepage control in the dam foundation using Larsen IV steel sheet piles, combined with construction piles as anti-seepage barriers. It will repair voids beneath the beam frames of the sluice gates, reinforce scour holes and the downstream channel bed, replace and repair multiple sluice gates, and replace both the upstream and downstream lock gates of the ship lock chamber. The project will also install new hydraulic cylinders for the operation of the main sluice gates and the water inlet/outlet gates of the lock chamber, upgrade and repair the electrical control system for the gates and the management house, renovate the traffic bridge, lighting system, and signage, as well as establish a monitoring system to support the dam’s management and operation.

According to the managing unit, the maintenance, repair, and servicing of the dam have been carried out annually. However, due to limited funding, existing issues have not been fully addressed. By 2023, an urgent repair project to ensure the safety of the Thao Long Dam had been approved by the former Ministry of Agriculture and Rural Development, with construction scheduled to begin in early 2024.

However, subsequent on-site inspections by the competent authorities revealed that many essential components had severely deteriorated. As a result, the project’s implementation had to be postponed to allow for a comprehensive, thorough, and cautious assessment of the dam’s current condition and quality.

At the end of July 2025, during a field inspection of the Thao Long Dam, Deputy Minister of Agriculture and Environment Nguyen Hoang Hiep affirmed that the Ministry had approved the repair of the dam to ensure the safety of the structure, maximize its operational functions, and enhance proactive management and operation.

"The People’s Committee of Hue City must direct relevant departments, local authorities, and units to closely coordinate with the project investor during the management and construction process to ensure the project’s progress. The investor is required to carry out its functions, powers, obligations, and responsibilities in strict accordance with current regulations. During construction, close attention must be paid to weather developments to ensure the dam continues to prevent saltwater intrusion, retain freshwater, and regulate water resources for agricultural production and household use in downstream areas," the Deputy Minister emphasized.