Here is the list of all the estuarine reefs from the DMF website:
http://www.ncfisheries.net/reefs/estreefs.htm
When I was working in the North River a few years ago, they were taking a barge loaded with oyster shells out once a week or so and dumping them somewhere to start a new reef. You can use the ‘Contact DMF” button at the top of the page, and you can click on “Oyster shell recycling” to find out more about that. I suspect there are more oyster reefs than the ones shown on the map. You might be able to find some using the “Contact” button. Good luck. chip.