A book, “Monster Spotter’s Guide to North America” by Scott Francis (2007) states that the Oklahoma lakes are inhabited by a carnivorous creature , appearing as a reddish-brown Octopus with leathery skin and measuring more than 20 feet long. An extract “Lakes in
So possibility or hoax?. On the plus side there is species of jellyfish have been able to adapt from saltwater to freshwater conditions, and the same adaptation may have been possible for other creatures. For example eels travel between salt water and freshwater habitats so a freshwater adaptation of a species is not totally unknown in a salt water species. So far however a Fresh water Octopus has not been discovered. The Bull Shark is a ocean dwelling creature that has been found in freshwater and can be dangerous and will attack people. The lakes though are man made and have not been open to the sea as far as I can ascertain, so the only way a species from a salt water environment could be in there is if someone put it there, perhaps a pet that out grew it’s home. It seems more likely that there is some other explanation for the high number of drownings. It has been suggested alcohol is involved , or maybe there are some underwater debris or currents that ensnare swimmers. Unless a freshwater octopus is discovered , that is what the deaths will be put down to and to be honest seems the more likely explanation.