Ruth Young writes to say that the canal has now been placed on the Tasmanian Heritage Register which records "those places that are recognised as being of historic cultural heritage significance to the whole of Tasmania".  On a recent expedition to the banks of the canal the grandson unearthed a pirate beer bottle AND a pirate cigarette lighter.  It may have been these sorts of discoveries that swung it. For more on the canal and on the controversy about putting a pipeline through it a couple of years ago see this item written by Chris Wilson: http://www.lbt.org.au/The_Egg_Island_Pipeline.html.