An engineered ecosystem
In 1807, King Sri Wickrama Rajasinghe, the final monarch of the Kandyan Kingdom, ordered the creation of an artificial lake in Kandy. This project was not decorative; it was a significant act of geoengineering that permanently altered the local environment. The site was originally a stretch of terraced paddy fields known as Tigolwela. The king commissioned his architect, Deveda Moolacharya, to dam the fields, converting productive agricultural land into a large reservoir. This decision met with strong opposition from local advisors, who objected to the loss of farmland and the use of forced labor.
The resulting lake, known as Kiri Muhuda or the "Sea of Milk," covers a surface area of 19.01 hectares (47 acres) and holds approximately 867,000 cubic meters of water. It has a maximum depth of 18.5 meters and a perimeter of 3.4 kilometers. The construction involved building a substantial dam, parts of which were later developed into a roadway. This new, large body of water introduced a massive thermal mass into the valley. Water heats and cools more slowly than land, a principle that moderates the temperature of the surrounding air. Research on urban climates in Kandy confirms that the lake influences local thermal comfort, creating a distinct microclimate. The increased surface area for evaporation also raises local humidity levels.
Unintended biological consequences
The creation of Kandy Lake had lasting effects on the region's biology and public health. Before the lake, the area consisted of managed rice paddies, a specific type of wetland ecosystem. The permanent and deeper body of water created a different habitat. While aesthetically pleasing, the lake became a breeding ground for mosquitoes, vectors for various diseases. Historical public health records from the British colonial period, which began shortly after the lake's completion in 1815, document the prevalence of diseases like malaria and hookworm infection in the central highlands. While not solely attributable to the lake, the creation of a large, static water body in an urban center would have changed the distribution and density of disease vectors.
The lake's ecology continues to be a subject of scientific interest. It is part of the Mahaweli River catchment, Sri Lanka's longest river system. Urban runoff and wastewater discharge have led to significant pollution and eutrophication, a process where excessive nutrients cause dense blooms of organisms like cyanobacteria. Studies have documented high levels of organic matter and pollutants, with water quality varying between eutrophic and hyper-eutrophic states. In recent years, scientists have deployed floating wetlands with plants like Canna species as a biological purification system. These platforms have been shown to reduce water pollution levels by as much as 60% per cubic meter by absorbing excess nitrogen and phosphorus directly from the water.