Ganga in Kolkata

The main branch of the Ganges, the Padma, passes through the Farraka Barrage, a gigantic barrier designed to divert the Ganges waters into the Indian Hooghly branch, and away from the Padma. Completed by the Indian government in the early 1970s, it was intended to help flush out the increasing silt deposits in the Hooghly, to improve navigation, and to provide Kolkata with irrigation and drinking water.
About 150 large industrial plants are lined up on the banks of the Hooghly at Kolkata. Together, these plants contribute 30 percent of the total industrial effluent reaching the mouths of the Ganges. Of this, half comes from pulp and paper industries, which discharge a dark brown, oxygen-craving slurry of bark and wood fiber, mercury and other heavy metals which accumulate in fish tissues, and chemical toxins like bleaches and dyes, which produce dioxin and other persistent compounds.