If you don't have a huge filtration or water purification system for it, you should consider areas where you can put plants to act as a biofilter.

How puncture resistant is PVC? I have seen some liners from these guys (they make liners to be used in ski parks and water ski lakes) and they are TOUGH!!

http://www.btlliners.com/liners/recreation-pond-liners/

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).