Cecil:
Sure as a simple survey method that's a good idea. My experience with range finders is limited to the target range, golf course and field trials but I'm sure it would work well for simple pond shapes and would be faster than a measuring tape. Complex shapes like my pond would be a problem because you would need multiple targets around all of the bays and points, which would be a logistical nightmare not worth the effort.
You could do what Bill mentioned and use the rangefinder to shoot a rectangle (or even a radius) that contains your pond and use that as a maximium value and then adjust downward.
Of course there is error associated with all these methods except differentially corrected survey grade GPS or traditional survey methods, which are I think are beyond the investment we're talking about here.
Once I received my aerial photograph it took me about an hour to calculate the area of four ponds. I had to do it because the regulator who was reviewing my permit renewal accused me of having 12-acres of water, when I was only permitted for 5. Turned out to be three just like we had told him on the application. Three down, two to go.
