It is estimated that 80% of all is untreated and flows directly into india's rivers, making it a major source of water pollution

Raw sewage

Explanation:

About the 80% of the untreated water that falls in the Indian rivers has its source in the industrial districts and they are heavy use and chemical abusers of the degraded and degenerate waters and they dump these toxic wastes in the sewage system that flows directly to the rover ecosystem nearby and created water-born diseases.

b.   jim crow laws were enacted in northern states.