Blackwell campground is very nice - surprisingly well-maintained with unique sites, many of which are large and private.  Some have large lawn areas as well as nice wood-chip pads, while others are mostly gravel.  All look very level.  Bathrooms and shower house are clean and also well maintained and water is available at quite a few spots.  The main road throughout the camp is mostly large gravel - keep that in mind if you're walking to the shower house, your flip-flop shower shoes are probably not going to be comfortable! 

Note that you have to drive over 5 speed bumps throughout the preserve to get to the campground.  The preserve itself is large and one of the best in the area, with boat rentals, hiking trails, picnic areas, and even an archery range.   It's in the middle of a suburban area with lots to do nearby, so you'll get great cell signal and unfortunately lots of road noise.