I think I've heard that the river might need some cleaning up before the Olympics;
so I remembered some people were doing this in the oceans !
I don't know whether these would help; but these are some of the Ocean cleaning up initiatives and some of their "ships" might be useful ?
http://theoceancleanup.com/
and another one
( Not that I'm being critical of France; because surely the US has gotten places polluted too much in our own country ( which I should be able to say, because I am an american ! )
These boats or something like them might be able to help the river in time for the Olympics start !