I would contact online rescue groups. It's amazing how many people you can reach that way. Email them the best description you can, and post a picture on a website somewhere and put a link to it. Don't attach a picture, bacause many lists can't take attachments.
Watch the paper for a 'lost/stray' ad.
Unfortunately, some dogs get loose while people are on vacation, so the dog could be owned by someone who was just passing through the area.
Your biggest 'audience' will be the internet.