Lake Mungo is purely fictional. It doesn't draw from real events. The story is designed to engage viewers with its suspense and horror elements rather than being rooted in truth.
In a way, it is. The movie takes some cues from real-life occurrences and builds a fictional story around them. However, it also adds fictional elements for dramatic effect.
In fanfiction, 'Draco' might refer to a character, often from the Harry Potter series. 'Chains', 'plugs' and 'clamps' could be elements used in a very creative or perhaps kinky context within the fictional world of the fanfic, but without more specific context, it's hard to be more precise. It could also be part of some unique magical or non - magical contraptions in the story.