Where to find supplies to float a dock.

I purchased a house two years ago that had a nice 10x10 dock that was built off the backyard into the creek that runs behind my house. The water tends to rise a lot when we get our normal Louisiana thunderstorms and the front legs of the dock were broken when the dock rose too high on the water a few months back. I want to convert the dock into a floating dock and was wondering were I could find industrial size barrels or floating styrofoam blocks around the Baton Rouge/Gonzales area? Any help or experience with this is appreciated.

Google has been helpful in finding some well thought out plans on how to install both, I just have no idea where to look for such things.