Ok, here is a view of the other end of my little pond (from the east...our main seating area of our deck is to the west, and our bow window view is from the south...looking north towards the lake). When I took these photos, I was standing just outside my walk-out basement door. The retaining wall you see (partially dismantled in this view), is behind and below the spot where my new waterfall will be, supporting the soil bank under the deck in back of our home. While trying to design the shape and size of my planned cascading waterfall, I got worrying about that retaining wall. It's been rock-solid there about 20 years or so. But now the pond is bigger, and the edge comes closer than it did before. And, when I took out a couple of blocks to remove an old abandoned electric cable that ran through the wall, I found most of the cavities between the concrete blocks completely packed with hard clay, plus a few cavities which were obviously old rodent nests (most likely mice and/or chipmunks...maybe the same culprits who chewed through my previous pond liner!) I concluded that water in the soil would need to be able to weep out through those retaining-wall blocks, and packed mud wasn't going to let it flow well enough. So, as if I didn't have enough to do already with this project, I dismantled the entire wall behind the waterfall, lifting out every block, and digging away the packed-in clay and anything that looked like a nest. Man, those blocks are HEAVY!