A stretch of the Greenbelt was closed here in town for 3 or 4 months over the winter. And this is what they put in - a water park, designed to appeal to kayakers and such. It apparently has an adjustable water stream that can alter the size and/or shape of the waves. I haven't been around when they've been changing it, but that sounds pretty interesting.
It's already attracting water-goers, even though the river is right at flood stage, and probably only 40 degrees or so. Check out the first photo in particular - I admire the guy who brings his boat to river's edge by bicycle! My kinda guy! The other two photos were taken a few days later from the opposite side of the river... and with some rather ominous clouds above.