I have another Labyrinth Lord release from Fat Goblin Games at the OBS sites.
http://www.rpgnow.com/product/135258/Bestiarum-Vocabulum-Freshwater-Monsters--Hazards
In monster design, freshwater habitats (especially the smaller bodies) are one location series that’s often neglected. To help Game Masters looking to add a few little (or not so little) surprises to their ponds, streams, and wells, here is a selection of monsters and living hazards.
Bestiarum Vocabulum: Freshwater Monsters & Hazards provides you with detailed accounts of a variety of lake, river, and stream creatures as well as the hazards of those areas.