This is the weir at Gatineau the day we first saw it, the 17th May 2008. (If you click on the link you can see it quite clearly on the arial photo, just north of the racecourse.)
Here it is (or rather; here is isn't) 12 days later - after 10 days of on and off rain.
Three months later, and the river has dropped enough for small wading birds to be running up and down the weir.
Why there is a weir and a complex of abandoned buildings here is still a mystery to us.