I know a lot of people go to Alum Creek which I think your lab would love because there's water access. There's also one in Georgesville (the town not the road =) that you can take your dog to, but I believe they have to be on a leash (pretty sure it's part of darby creek park). This was on the news the other night and caught my attention.
http://www.nbc4i.com/midwest/cmh/news.apx.-content-articles-CMH-2008-06-16-0032.html
I guess developing bad habits from other dogs from dog parks is like, kids getting bad habits from others at playgrounds. As long as they know you're the alpha male and you show it at home after you take him out to play with other dogs, I think he'll be just fine. He's young enough that you should be able to teach him good habits and he'll forget the bad.