Originally, When USA was in the making. Early settlers wanted people to migrate. That was the policy.

@Convivial Don't give me one exception, please. Americans, Europeans, Australians and Africans keep their rivers clean.

@Horsefrost only in the last 100 years... Before that they were convenient sewers...

@Convivial Before that also, rivers were never dirty. River has a tendency to self cleanse upto a level just like forests.

@Horsefrost not if left to their own, that happens only after something terrible is discovered to have occurred and regulations are developed!\

@samueltyler2 Forests can indeed heal themselves through various natural processes. Research has shown that damaged forest ecosystems can recover with surprising speed and fullness, especially when there is sufficient nitrogen, which plays a major role in the formation of cells in many organisms. This ability to regrow is evident in young trees that accumulate biomass quickly, demonstrating the remarkable capacity of forests for regrowth after damage.

@samueltyler2 Yes, rivers can self-clean to some extent through natural processes. This ability is known as self-purification or self-cleaning capacity. Rivers have various mechanisms that help in cleaning themselves, including biological, physical, and chemical processes.

Biological processes involve the action of microorganisms, such as bacteria, which break down organic waste using dissolved oxygen (D.O.) in the water.
These bacteria convert organic waste into inorganic matter, which can be used as nutrients by plants and other organisms.

Physical processes include dilution, where the mixing of wastewater with stream water reduces the concentration of pollutants.
Additionally, the velocity of water, depth, and turbulence affect the self-cleaning potential of the river.

@Horsefrost yes, what is your point? with diversity though the ecosystem thrives better. Each year we increasingly are losing species. We do not know how much is from human-related activities, but when we cut down rain forests it will take hundreds, if not thousands of years, if ever, for them to reaccumulate.

@samueltyler2 I was talking about rivers.

@Horsefrost thanks for the information. do you believe that you are the only one who knows this? do you think the scientists wo proved much of what you stated would suggest just allowing industry to pollute rivers so that the rivers can simply recover by themselves? How much human disease will be caused during the time the rivers recover?

I simply did googles for these, you can do the same. Please don't argue saying these are leftist reports, That is a diversion and cop out.

You are old enough to remember the disaster in W Virgina when coal ash contaminated the river
https://weather.com/science/environment/news/west-virginia-chemical-spill-exposes-new-risk-water-coal-20140118

how about the lead contamination in Flint, Michigan
https://www.nrdc.org/stories/flint-water-crisis-everything-you-need-know

Dupont's contamination of water over years:
https://www.timesunion.com/capitol/article/dupont-agrees-settle-lawsuit-hoosick-falls-water-20400391.php

@Horsefrost nice try!