I'd place a 5 gal bucket in the pond in very shallow water. Fill it to the brim, and monitor rainfall vs. evaporation rate in the bucket vs. rainfall + runoff -evaporation and possible leakage in the pond.


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).