Securing flat pond edge stones

[Cypress Point Pond]

There are several flat pond side stones that consistently slip into the pond due to the slope of the ground.  The pond liner extends under these stones and the grass.  One option I'm considering is to adhere these specific flat stones to the pond liner using spray foam.

What is your opinion?

[howardTheHumble]

I would flatten the ground under the liner, or add some dirt under the liner to bring it up to level. 

[GarryT]

I've used the spray foam for this purpose and it works quite well - as long as the liner and the stones are thoroughly dry when you apply the spray foam. If the sones are porous the foam will let go after some period of time (a year or two) but otherwise it seems to work OK.

[Cypress Point Pond]

The liner runs past the stones undergrown.  The stones are not porous and both the stone and liner will be dry before spraying on the foam.

Thank you both.

[Tadpole]

Have you tried creating a slight slope away from the pond edge? I do this even on pond shelving with great success.

[Cypress Point Pond]

Thank you all.