Thank you all for your thoughts. Gehajake, yes it will be cut out of virgin soil, so I'm wondering how steep.

Esshup I agree with you that islands can create a lot of headaches. I am hoping I can keep the geese off, as I would like to give the kids something to swim/boat "around". It is also a dugout so I don't have room for the extra soil anyways, so I won't lose any water volume that I could otherwise gain.

2:1 sounds reasonable. I was thinking I could maybe get away with 1:1, but maybe that is too aggressive. I don't think I should have any waves nehunter as you point out, as it is only 1.5 acres in total.