Hope alot of people respond to this as well but here is my two cents worth
In a few months I will be building an 8.5 acre lake at 30 feet deep. So I better know what I am talking about!

1. Very large Track Hoe "Excavator"
For digging core and extracting clay for dam
2. Real good Dump Truck
For moving and placing dirt and for compacting dirt after it is placed
3. Tractor Loader backhoe
For clearing all topsoil under the foot print of the dam site. Also, for over all shape up and any other misc tasks.
4. Possibly a vibarating sheeps foot. this depends on how well you can compact with the dump truck. May not need this.

these are ordered importance first.

could always use a track loader or a dozer.