Okay you critter experts...what was in my pool this morning?? It quite obviously enjoys swimming. He has been safely relocated to the creek down my street, hopefully no worse for the wear. He has webbed feet. Here are some pictures:
http://areias.zoto.com/img/45/bc9b55...eeb7e74d9-.jpg
http://areias.zoto.com/img/45/91c942...5704f4d9b-.jpg
http://areias.zoto.com/img/45/9dcd26...e9e4f0d28-.jpg
I'm fairly sure it's not a Knarp Rodent, so please spare me that.