I just bought a pair of AStars Toucan (stupid name) boots. They feel great! Not sure on the waterproofness but if it says GoreTex it is usually pretty good. These boots are very light weight, lots of protective plastic and hinged for your ankle's pleasure. It will be a big hit to the wallet but you pay for what you get.
Other options in waterproof offroad are the Sidi Adventure, Forma, Gaerne and TCX. Good luck in your search.