> Surely the religious leadership is not happy with that.

Hindu religion is not like Catholic Church. Unfortunately, in such issues, it is very fragmented and 'decentralized' with multiple different sects, castes, pontiffs etc.

Uttar Pradesh, where Ganga mostly flows has a lot of water heavy low-tech businesses. Leather tanneries is the first thing that comes to my mind. Illiteracy doesn't help either.

Things are changing. Ganga in Varanasi and a few other areas are much cleaner in the last couple years than they have been in the past!