Welcome to the forum! You have a lot of watershed, you will need a big overflow pipe. To help adjust the level of water in the pond you could either use a siphon drain where you can manually start the siphon and stop it when you reach the level you want, or look into a Flashboard Riser system if you have water continually going into the pond - it will allow you to adjust the level of water by adding or removing boards.

Agri-Drain makes the Flashboard riser systems.


www.hoosierpondpros.com


http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).