With regard to fertilizer, having a pond in virginia is definatly a different situation than many ponds in the mid-west that have exclent fertility naturaly. I would say if your water is pea green with visibility around 18" naturaly than do what you can to restrict the nutrents in your pond. If not than I would assume that you are fertilizing anyways and the runoff from fertilizing your lawn would be a bonus. I've been puting all the phosphorus I can get my hands on into my VA pond and still cant get my visibility shallower than 36". So if your pond is anything like mine I wouldn't wory about your pond over-blooming as a result of the run off from your lawn.

hope that helps
-Scott


Take great care of it, or let someone else have it.