Jack,
I believe most pondmeisters on this forum are kind of partial to earth type dams.
Use good soil material for construction and compact it properly.
A 3:1 front slope and at least 3:1 back slope should suffice. Use a flatter slope for the back slope if you ever anticipate dam over topping. Plant good sod forming grasses on the structure to help prevent side slope washing and erosion.
I have been really satisfied with principal spillway (Pipe works) from agri-drain for projects like yours. Probably the "Inline water control device"
http://www.agridrain.com/ Sounds like a very nice project.
Ed
