Dr Sarath Obeysekera 

https://adaderana.lk/news/cmrddx0sv000b356q294bse8d

The reported proposal to pump seawater into Beira Lake as part of its restoration has generated considerable public interest. While improving the water quality and reducing pollution are commendable objectives, introducing seawater into what has long functioned as a predominantly freshwater urban lake raises important environmental, engineering and economic questions that deserve careful scientific evaluation before implementation. (Wikipedia)
Sri Lanka has previously witnessed the unintended consequences of altering the salinity of wetlands. One often-cited example is the Dutch Canal system, where the intrusion of seawater into surrounding wetlands contributed to long-term salinity problems, adversely affecting agriculture in areas such as Muthurajawela. Once salt enters soils and groundwater, restoring the original ecological balance can be extremely difficult and costly.
A similar concern exists with Beira Lake. Increasing the salinity of the lake may have several long-term consequences.
First, seawater is highly corrosive. Chloride ions accelerate the corrosion of reinforcing steel embedded in concrete. Around Beira Lake stand numerous high-rise buildings, bridges, retaining walls, jetties and other infrastructure. If saline water increases the chloride content in the surrounding environment, it could accelerate the deterioration of reinforced concrete structures, steel sheet piles, pipelines and waterfront facilities. Repairing chloride-induced corrosion is among the most expensive forms of infrastructure maintenance.
Second, the ecological consequences require careful investigation. Over many decades, Beira Lake has developed its own ecosystem of fish, birds, aquatic plants and microorganisms adapted to existing water conditions. A sudden or sustained increase in salinity could alter species composition, reduce biodiversity and encourage the growth of organisms better suited to brackish conditions. Ecological changes of this nature are often irreversible. (Wikipedia)
Third, groundwater impacts should not be overlooked. Saline water can migrate through porous soils and affect groundwater quality in adjacent areas. This may influence landscaping, urban vegetation and even underground infrastructure over time.
It is also important to ask whether pumping seawater addresses the root cause of Beira Lake’s problems. The lake’s deterioration has primarily resulted from decades of untreated wastewater, stormwater pollution, nutrient enrichment, sediment accumulation and illegal discharges. Unless these sources are comprehensively controlled, introducing seawater may simply dilute pollution temporarily without providing a sustainable solution. Previous restoration strategies have focused on eliminating pollution sources rather than fundamentally changing the lake’s water chemistry. (Wikipedia)
Before proceeding with such a project, the Government should commission a comprehensive Environmental Impact Assessment (EIA) conducted by independent experts. The study should include:
● Hydrodynamic modelling of tidal exchange and salinity distribution.
● Long-term impacts on aquatic biodiversity.
● Corrosion risk assessments for surrounding buildings, bridges and utilities.
● Effects on groundwater and adjacent soils.
● Economic cost-benefit analysis comparing seawater pumping with alternative restoration methods.
● Public consultation involving engineers, environmental scientists, urban planners and local stakeholders.
International experience shows that urban lake restoration succeeds when pollution sources are eliminated, sediments are managed, wetlands are restored and water circulation is improved using scientifically validated methods. Artificially altering salinity should be considered only after demonstrating that it offers clear long-term benefits that outweigh the environmental and engineering risks.
Beira Lake is one of Colombo’s most historic and iconic landmarks. Any intervention must therefore be guided by sound science rather than expediency. Decisions taken today will affect the city’s infrastructure, biodiversity and environmental resilience for generations.
Sri Lanka should embrace restoration based on rigorous environmental science, comprehensive engineering studies and transparent public consultation. A detailed Environmental Impact Assessment is not merely a regulatory requirement—it is an essential safeguard to ensure that well-intentioned solutions do not create irreversible problems for the future.

Regards

Dr Sarath Obeysekera