The Monsey/Rockland Eruv map indicates one large karfif (in red). A karpef/karfif is as an area not designated for residency which invalidates an encompassing eruv if it is not itself separated by a distinguishing barrier and is greater than 5000 square amoth (~10,000 sqft.; see e.g. here) However, the Rockland eruv seems to be filled with many such wooded and unused areas (e.g. here, here, here, etc.) or lakes (e.g. here, here, here, etc.). So what distinguishes the demarcated karfif from these other uninhabited areas?