Because of its unique chemical structure, water dissolves almost any substance and thus is easily polluted. Environmental pollution continues to escalate in emerging economies such as in Sri Lanka. This is aggravated by anthropogenic activities, including deforestation, soil erosion, and irresponsible use of agrochemicals, and overuse of phosphate fertiliser. The latter has led to leaching of large amounts of phosphate from vegetable farmlands in hill countries into streams, and eutrophication of irrigated reservoirs in dry zone. This has become an important environmental issue in low elevations in the dry-zonal areas in Sri Lanka. This unhindered environmental damage is mainly caused by the reckless use of fertiliser secondary to large governmental subsidies, which encourage farmers to overuse fertiliser. Since the excess phosphate fertiliser added would not retain in the soil, these leach out into the waterways ending up in waterbodies, including reservoirs. Excess phosphate in water facilitates cyanobacterial algae blooms, which have significant adverse effects on freshwater marine life and perhaps, in people, Governments and society must initiate actions to protect and preserve the precious watersheds, curb the overuse of agrochemicals, and preserve watesheds and the environment for current and future generations.