I have seen black and white photos of Chennai from the early 20th century.  Coovam was not always a smelly, dirty river.  Once upon a
time it had fish and other living beings in it.  Clean water used to flow in it.  Today, no life can survive it.  I suppose almost every
third world city has a Coovam.  What is third world without it. 

Every now and then there are talks of cleaning the Coovam.  Even this week there were reports about building check dams across it. 
Coovam originates in the west of the city and it is not polluted. By the time Coovam meets the sea it is highly polluted. 

I would assume that in a water starved city, there would be enough interest in recovering the water from the sewage.  And/Or pump sea
water in and boats could provide transportation and touristy trips on the river. 

Bangkok’s Chao Praya river does all this, except the sea water part.  The view of the city and the temples from it is beautiful.  Come
to think of it, pretty much every romantic and beautiful city in this world has a river running through it.  And many of them were not clean
as they are now.  So there is hope for Coovam too.  May be we can learn a few tips from Seoul.