You'll have to ask the water management people that question. You can also find out by checking with the fisheries department. Not sure where you are but I threw in a link just in case I'm right.
http://www.stjoeriver.net/
By the way, have you ever considered just using floating piers. It'll rise and fall just as the water will and will be less of a hassle. Just a quick thought, don't really know your situation there.
