It depends on the species and size of fish you are feeding. I feed BG in 3'-4' water max. Hybrid Striped Bass can be fed in 10' water depth. Throw the feed where wind will blow it away from shore, not back to it.

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.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).