Reasons for pollution of Ganga -
1) Dumping of untreated sewage
2) Dumping of industrial wastes and effluents in addition to human activities like bathing, washing, immersion of ashes or unburnt corpses etc.
This can prove to be harmful for people in the neighbouring areas as -
1) If this water is used for drinking, it will lead to many diseases.
2) People consuming fishes from Ganga will be very badly affected due to accumulation of the highest amount of poisionous and toxic substances because of biological magnification as humans will be at the top of this food chain in the case.