Complex sentence: The Central Pine Barrens overlays and recharges a portion of a federally designated sole source aquifer for Long Island's drinking water (all of Long Island's drinking water comes from ground water (wells))--none of the island's water comes from reservoirs.
Split into simpler sentences: The Central Pine Barrens overlays and recharges a portion of a federally designated sole source aquifer for Long Island's drinking water. All of Long Island's drinking water comes from ground water wells; none of the island's water comes from reservoirs.