I meant to add that i would put some structure in there now before it fills if you have not already done so. It looks like it was well constructed and hope you get many years of enjoyment from it. There is a unique satisfaction to raising a pond. Frustrating at times but not as hard as kids. good luck and enjoy.
There's a lot of clay there. They only compacted with the dozer as it was built up. That was done just before I read the wealth of info on this forum. With as much clay that went into the dam, I don't think there will be a problem.... I hope. I know I need to start thinking about some structure, but I've also been trying to rebuild an old cabin on the property for a place to stay when we're out there.
Structure is easy and I would do it now. After the pond fills it will be much harder. I did not have the bottom of my pond compacted when it was originally built 5 years ago and I have spent 2 1/2 times the money fixing it as compared to the original cost. Hopefully, you wont be that unlucky but do all that you can now before it fills. It will a lot cheaper in the long run. Best of luck and tight lines.