Does anyone know of a nice wedding ceremony/reception location in Northern VA?

The wedding is this August, and I'm not finding much in terms of availability. We're on a budget, and hoping to spend under about $10k for the entire wedding which will have around 50 guests. We're looking for something fairly informal, and we'd love to be able to get married near some form of water (large pond, a lake, river, etc.), but with the exception of a small golf course pond (which reminded me of a drainage ditch), we haven't been able to find anything else that's still available (and I've been pouring over search results for months now). Any thoughts?