DIY LR curing in a lake?

I was wondering about do my own LR and to cure it in the lake behind my house. its a natural lake.just a thought i dunno if it would cure it good enough. i figured after a month or 2 out there i can cure it on my own. anyone heard of this before or have any negs. or pos. to doing this

 

Lots of contaminants that will land on the rock, bacteria and other stuff will grow on it (and then die off when put into saltwater).

 

When looking into DIY rock I read of someone else who does the exact same thing you are wanting to do. They just put it in a cloth duffle bag with a rope, tossed it in for a couple months then took it out and cleaned it up.

 

well thats what i thought to the time to cure it in the lake would cause fresh water growth then to cure it in a tub with saltwater would kill the freshwater stuff then later place it in the main tank.thats my theory with it.