Eutrophication River

Water is a common sight in Shanghai, China.   Situated in a sub-tropical climate, the city is greeted many an afternoon with frequent deluges that, if experienced without an umbrella, can lead to one bearing a close resemblance to a wet rat.   As water flows through the city, it often looks like this:

One of my first thoughts when I see a body of water looking this way is... Where's the poop?  I realize I am not in a majority by having such a thought about a river flowing gently between its banks en route to a much greater, much larger body of water.  Some days, though, I think it might be better if a majority were having such thoughts while strolling over these eutrophied waterways.  Then, maybe, just maybe, more would be done about it.

It's ironic that eutrophication derives from a Greek word meaning healthy and adequate nutrition, when in fact, eutrophication implies that the nutrition is so much more than adequate that it has forced an ecosystem to fall wildly out of balance.   As too many nutrients are added to waterway soup, the simpler, less complex plants and organisms like algae and phytoplankton "bulk up", enjoying the excess of nutrients as we might indulge a delicious Thanksgiving dinner.  When indulged for an extended period of time, their bountiful diet leads them to reproduce more rapidly than normal, leading to an all too familiar coating of green on the water's surface.   While it may seem pretty to the un-jaded eye, this green coating represents a cycle heading wildly out of balance.  As the green things die, they sink to the bottom and decompose, consuming oxygen as they do, so much in fact that fishes and other oxygen-dependent aquatic organisms suffocate and die.   Compounding the damage to aquatic balance, the over-abundance of simpler plants and organisms prevents the more complex plants and organisms from thriving, thus denying food to some aquatic organisms while the simpler plants and organisms provide an over-abundance of nutrition to others.   As the cycle continues, biodiversity drops, taking the food supply and the overall health of the ecosystem down with it.

Not surprisingly, two of the most common sources of eutrophication are excessive phosphorous and nitrogen.  Sometimes, this excess derives naturally but more often than not, it comes from fertilizer run-off from farms or from poorly treated sewage.  In the large cities, where farms were long ago bull-dozed to make room for more people and an obsession with economic growth, only one logical source of eutrophication makes the top of the list 99 times out of 100.

Hence, the question:  Where's the poop?
And, the logical follow-up:  Why isn't it being treated?
And, the next thought:   When will it be treated?
And, finally:  Before or after we create yet another massive dead zone in our life-giving waters?