I must agree with you there !
It's one of the most polluted rivers in the world.
I once lived in Gangotri for a few months and walked a couple of times, about 4 miles, to Tapovan, the source proper of the Ganges river . . . it spouts roaring out of a huge "cavern" in the glacier that gives birth to it
The first town it sneaks through is Gangotri . . . you won't believe the filth they discharge in their "holy" river . . . not to speak of what they throw in it in all the other cities it goes through . . . until it reaches Benares (aka Vanarasi) . . . It truly is sewage by then.