Human excrement in rivers and running out into the ocean from coastal cities, from semi-deep drains like in Vancouver, is all part of the nutrients for the algae and bacteria blooms, along with red tides, that make the dead zones near estuaries.. The human excrement part is larger in Africa, and Asia, especially India and with it waterborne diseases, and 200,000 people in each large city who never use a real toilet in their lives. Only in few rivers is it a greater load than farm fertilizer runoff with uncomposted animal wastes. Recently in China, a river had 26,000 pig carcasses in it. The farmers could not afford to feed them any longer or dispose of them properly, and became pigs themselves, in a way. In the 1980s the North Sea had a massive fish die-off from the diminishing returns of increased chemical fertilizers in river runoff from fields, killing the entire fishery for 5 years and only getting back to 50% since then. The estuary dead zone problem didn't start to get bad until the 1970s when the Earth had half the overpopulation of today.
You can be talked into thinking urine is good to drink, and do it. We are all drinking dinosaur urine that has been naturally purified.
The other problems outside the estuaries such as the high plastic trash content in the Med and Black Seas, and the 6 huge oceanic trash gyres, the extreme over harvesting and throwing away of "garbage" species, the acidification from HGHGs hurting corals and shellfish and their eco-systems, high mercury content in top of the food chain fish, other chemicals and toxins, and generally noisier environment for sea mammals and fish, all to the point of odd beachings and local die-offs. Plus the warming of the oceans 0 to now 1400 meters deep, disrupting sea life and getting closer to rapid methane releases.
Other problems are hitting rivers and lakes with mercury fallout from dirty coal power of China and India and some from here when the rules were relaxed to appease big coal. It limits even the trout you can eat from pristine mountain lakes. Rivers have not been able to be cleaned up enough by upstream users, from various industrial and agricultural chemicals to birth control pill hormones which do some remarkable sex changes in downstream fish and perhaps, over time, other creatures. They get into farmed fish and are not checked enough for mercury and other toxics. Excessive salts in some irrigation rivers is destroying farmland by salination, while aquifer irrigation is getting close to empty and the loss of 5/6 of yields in affected areas. Already, conflict with water is common, and the cities win over the farmers in California and here this year in Colorado.
I do hope this is understandable to readers.
