hmmmm, i know several ppl from entre rios (my family on my father´s side is from there) that has gone and continues going to many of those demonstration from day one and they definately do not need any money, they are middle class folk along with many other ppl going with them. Looking at today´s live broadcast it was easy to see that most ppl there were middle class farmers/ranchers/businessmen, in short, locals, real locals and these ppl cannot be bought with a pancho and coca (which seems to be the currency on bought demonstrators hehe). There´s though, a while back, if i dont recall wrong, when they subject was very hot and had lots of press many semi-violent demontrations and many ppl being movilized for the "cause", i didnt pay much attention to it but it did sound to me like actions from corrupted politicians and their bullys, that may be what you are referring to, but as soon as the press got tired of it (since it became and endless thing) those incidents stopped ocurring or i never heard of them again. The truth i myself im not too knowledgeable on the issue, most of what i know is what entre rios folks told me.
on a side note, the riachule indeed, back several decades ago it was a clean river and ppl would swim on it until many plants like the one in Bosnia settled along its shore and started dumping all kinds of crap to the water (of course, CORRUPTION was a huge help) and it ended up becoming what it is now !! ....very sad !!!!!
The ppl in entre rios just dont want that to happen to their side of the river. In those parts, ppl still fishes there and even vacations there, they even have some beaches put together with lots of sand. To them is a very valuable asset and the thought of seeing it turned into the riachuelo makes them very sick, this i was told (and i saw it myself) by them, everybody, rich, middle class and poor.
If some corrupted politicians profit from this (they´re always looking for the next issue/conflict/deal they can profit from) i dont believe it should diminish the locals fight to preserve the river as it is now, clean !