Just above Fredericton is a dam. It is called the Mactaquac dam.
Bill found out this little tidbit of info about the amount of water that is going over the dam today.
Niagra Falls average flow rate: 202,000 cubic feet per second (source Wikipaedia)
Mactaquac Dam inflow on Saint John River today: 376,000 cubic feet per second (source government Riverwatch site [probably via NB Power])
We have a friend that lives up that way who sent Bill an image of the amount of water that is going over the dam and the level on the down side was only slightly lower than the water on the up side.