I see where your trying to get to and I do not think that tarp strips would be all that great compared to other non-natural items like rolls of old hog-wire fencing, sunken pallets, and cinder blocks, But, IF you could come up with a tarp that is made of a material that tended to float, you could roll up the tarp, bailing wire one end of the roll and cut the strips from the bailing wire to the opposite end, then secure it to a weight and sink to the bottom. This would simulate grasses. If the material did not want to float, I am afraid that you would end up with a pile of trash on the bottom of your pond.
