Pollution of the Ganges (or Ganga), the largest river in India, poses significant threats to human health and the larger environment.Severely polluted with human waste and industrial contaminants, the river provides water to about 40% of India's population across 11 states, serving an estimated population of 500 million people or more, more than any other river in the world.

Today, the Ganges is considered to be the sixth-most polluted river in the world. Raghubir Singh, an Indian photographer, has noted that no one in India spoke of the Ganges as polluted until the late 1970s. However, pollution has been an old and continuous process in the river as by the time people were finally speaking of the Ganges as polluted, stretches of over six hundred kilometres were essentially ecologically dead zones.

A number of initiatives have been undertaken to clean the river but failed to deliver as desired results. After getting elected, India's Prime minister Narendra Modi affirmed to work in cleaning the river and controlling pollution. Subsequently, the Namami Gangeproject was announced by the government in the July 2014 budget. An estimated Rs 2,958 Crores (US$460 million) have been spent until July 2016 in various efforts in cleaning up of the river.

Source: www.wikipedia.com