From what I know and saw when I stayed there for a bit, it's prevalent. Hang around at some NA meetings (the sketchier the meeting people there, the better), maybe a methadone clinic. There are some open air markets in the ghetto, too. In the early mornings, a lot of drug addicts congregate downtown to get like free food and coffee and whatnot, most are homeless tho, but you can start there.
I met lots of people in rehab there. Guys from Wilmington would have their ppl come by and slip us heroin and needles through the fence. Then when we got out, stayed with some ppl at their places. Good town.