I'm not an expert on your issues. I have used foam to prevent water from running under (rather than over) rocks. BTW, 'Great Stuff' is the same stuff as the black foam, only beige, and cheaper. I would expect that Gorilla Glue might work, but it might have the same issues for you. Like you are thinking, I use drift wood logs in my stream. I would suggest that you could just expect deterioration and as you are out and about, simply keep your eye out for potential replacements. You might want to try 'sweet flag'. It will grow in water and can attach to liner. The problem is that it can take over. However, it can anchor well enough after awhile to support other items like driftwood.

Hi

They make a 3 dimensional liner that is embossed to look like stone . Have never used it but in your case you could put it over the real liner ?? Forgotten the name of the product but any pond supply store would probably list it??

gary

I would not try to glue rocks to liner that you are planning to hang vertically. The weight would be too great and the liner would stretch and probably tear, if you could even get the rock to stick.

Can you post a picture of your problem area - a visual would help!