Just had a new pond constructed and used bentonite clay to line the pond. I am still trying to determine the proper water depth (ie what level the clay was lined to) and was wondering if the seal is immediate or if takes time for the seal to work?

Also, how far up the bank should the water level go up to? The constructor told me about two feet below the top of the bank.

It should take some time for the seal to work but I don't know much about pure bentonite. Did he line the walls and the bottom? Everything leaks to some extent. This stuff isn't a plastic liner.

If he says 2 ft from the top, that's where he has built an overflow area. Or has built the dam 2 ft higher with the exception of one side area that is 2 ft lower.