Who left that there?

Rose has school on Tuesdays so after I put the kids on the bus I often go for a walk.  This morning I moseyed off down to our neighbourhood beach.  What a mess its in, there were bits of tree and dead fish where ever you looked.  This way

and this way.

I hope it self cleans before swimming weather or its going to be a nightmare getting the kids clean before we set off home and I don't fancy all that tree debris in my trainers, sand is bad enough.  It was remarkable that in amongst all this stuff there was very little in the way of man made rubbish, just a couple of bottles and cans and a few pairs of shorts?  Next time I might be a good citizen and take a rubbish bag.  This was the obvious exception

I think it is an escaped boat dock, I hope the boat wasn't fastened to it when it broke free.  Also I wonder where it came from, Lake Huron has a shoreline length of 3,827 miles (just less than the coastline of Ireland) so it would be very disappointing to find that it floated up 5 miles from Port Franks.