are you talking about high tension lines or just like the service to your home or something like that. we have a set of high tension lines running thru our property, the power company has a right of way thru there, we own the land but they have the right to come in and work on the lines whenever they need to etc. there is restrictions as to what can be done on the right of way, no permanant structures, they must be able to get thru there access road and that sorta stuff. you would have to call them to find out what the deal is for a pond on the right of way, i would imagine it would be ok as long as it wasnt too close to the poles and they could still access the lines. one other thing to keep in mind is that very often there are ground wires running thru the ground under the lines to ground the top wire and other apparatus, these are not very deep usualy, i have snagged a few with the dozer taking out tree stumps and brush, and my father even hooked one with the brushog once so before you dig double check about that too