I normally do my tripping in the summer so I tend to wet foot it and use OTB boots.  However I'm heading up to Algonquin for the beginning of October so worst case scenario, I may be encountering conditions that may well be similar to what you'd meet in May, namely wet and cold.  I'm giving Sealskinz waterproof socks a try coupled with Wigwam liner socks and just use either my OTB's or my Keen H2O sandals.  This is mostly so that I won't be reticent about stepping into the water when putting in or taking out.  At the camp site, spring, summer or fall, I'm always sure to have a backup dry pair of some kind of shoes and at least a couple of pairs of wool socks.