Polluted river flowing through an industrial landscape.

Kelani River Under Pressure: How Pollution Control Can Save Sri Lanka's Lifeline

Lena Voss in Climate & Environment June 2025 • 4 min read.

"A deep dive into the industrial pollution plaguing Sri Lanka's Kelani River, and the innovative modeling strategies offering a path to cleaner waters."

The Kelani River, the fourth longest in Sri Lanka, is under increasing environmental stress. Supplying 80% of Colombo's drinking water, this river faces threats from rapid urbanization, industrial development, and inadequate waste management infrastructure. The consequences of this pollution extend beyond ecological damage, impacting public health and economic stability.

For years, the Kelani River has suffered from the harmful effects of industrial discharge and domestic waste. Current regulations have not fully addressed these problems. Industries often release untreated or partially treated effluents directly into the river, leading to elevated levels of pollutants like biological oxygen demand (BOD) and reduced dissolved oxygen (DO).

This article examines the findings of a comprehensive study that uses integrated modeling to assess pollution sources in the Kelani River. By combining catchment and river water quality models, the study offers new insights into how pollution affects water quality. It also provides data-driven recommendations for policies to improve river health.

What are Transfer Coefficients and Why Do They Matter for the Kelani River?

Polluted river flowing through an industrial landscape.

A key element of the Kelani River study involves the estimation of transfer coefficients (TCs). These coefficients act as essential metrics, quantifying how a unit of pollutant released in one area impacts water quality in another. By calculating these values for different zones along the Kelani River, researchers developed a detailed map of pollutant transport.

Transfer coefficients offer several practical benefits:

Targeted Policy: TCs help in designing effective environmental regulations by identifying the most critical pollution hotspots.
Industrial Planning: Planners can use TCs to assess the environmental impact of locating new industries along the river.
Resource Allocation: TCs assist in allocating resources for pollution control, ensuring that efforts are focused where they will yield the greatest improvements in water quality.

The study revealed significant differences in TCs across various zones of the Kelani River. The upstream zones, closer to industrial parks, showed higher coefficients, indicating a greater impact on water quality. These findings emphasize the necessity for stricter pollution control measures in these areas.

A Call to Action for a Cleaner Kelani River

The Kelani River study provides actionable insights and recommendations for improving water quality. Implementing these strategies will require collaboration among government agencies, industries, and local communities. Prioritizing sustainable practices and investing in wastewater treatment infrastructure can lead to a healthier, more resilient Kelani River, ensuring water security and environmental well-being for future generations.

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Everything You Need To Know

What are the primary sources of pollution affecting the Kelani River?

The Kelani River faces pollution primarily from industrial discharge and domestic waste. Industries often release untreated or partially treated effluents, leading to elevated levels of pollutants like biological oxygen demand (BOD) and reduced dissolved oxygen (DO). Rapid urbanization and inadequate waste management infrastructure also contribute significantly to the river's pollution problems.

How does the study assess pollution sources in the Kelani River?

The study uses integrated modeling to assess pollution sources. It combines catchment and river water quality models to provide insights into how pollution affects water quality. A key component involves estimating transfer coefficients (TCs) to quantify how a unit of pollutant released in one area impacts water quality in another. This helps in understanding the transport and impact of pollutants along the Kelani River.

What are Transfer Coefficients (TCs) and why are they important in managing the Kelani River's pollution?

Transfer coefficients (TCs) are metrics quantifying how a unit of pollutant released in one area impacts water quality in another part of the Kelani River. They're essential because they allow for targeted policy interventions by identifying pollution hotspots, aiding industrial planning by assessing the environmental impact of new industries, and helping in resource allocation for pollution control efforts, ensuring they are focused where they yield the greatest improvements in water quality.

How can the findings of the Kelani River study be used to improve water quality management and environmental regulations?

The Kelani River study provides actionable insights and recommendations for improving water quality by using transfer coefficients (TCs). By identifying critical pollution hotspots, environmental regulations can be more effectively designed and enforced. Planners can use TCs to assess the environmental impact of locating new industries along the river. Additionally, TCs assist in allocating resources for pollution control, ensuring that efforts are focused where they will yield the greatest improvements in water quality. Implementing these strategies requires collaboration among government agencies, industries, and local communities.

What are the long-term implications of pollution in the Kelani River, and how can strategic pollution control help ensure a sustainable future?

The long-term implications of pollution in the Kelani River extend beyond ecological damage, impacting public health, economic stability, and water security. Without strategic pollution control, communities relying on the river for drinking water face health risks, and economic activities dependent on clean water suffer. By prioritizing sustainable practices, investing in wastewater treatment infrastructure, and implementing the data-driven recommendations from the Kelani River study, it's possible to ensure a healthier, more resilient Kelani River, securing water security and environmental well-being for future generations. Effective pollution control measures and use of tools like transfer coefficients (TCs) can help mitigate these negative impacts and support a sustainable future for the region.