Heck, if you can properly brace it so it didn't push out, you could make the dam out of 1/2" thick sheet steel and have a dam that is 1/2" wide. ..........
I'd like to see the muskrats try to burrow through THAT dam!
All joking aside, has anyone (esshup and others) seen a dam that used a vertical piece of pond liner to make the seal instead of a clay-packed core trench? I am imagining a situation where the pond site has very little clay, but you can reach a clay layer at the bottom of the core trench excavation.
Could you anchor the bottom of the pond liner in the clay and hang the liner against the trench wall, and then carefully backfill? You might have to make the dam a little wider than usual so your dam fill of sandy and gravel material could better resist the pushing force of the water in the pond.
