Is it possible to generate a set height contour for a proposed model?    For example, I have built a proposed site model. I don't know the footprint of the lake on the on my model in plan, but I do I know the water level on site is 29.150.   So, if I could generate a poly line at this height around the model, i.e. a contour line, I would be able to see the footprint of what will essentially be the lake and calculate area / volume etc?