May I add something to this?
Well, water is cheap; it's easy to build a swimming pool. But hell, if just an airplane falls on it, with benzene and everything else leading to a big fire, such as at the World Trade Center in 2001, the water goes away, the radioactive waste burns spontaneously, and you're dumping thousands or millions of curies into the air.
This would totally devastate the St. Lawrence River.
What do you think the Bloc Québécois people would do?