The Paulins Kill valley contains many protected areas. Swartswood State Park, established in 1914 as the first and oldest state park in New Jersey, is on just north of Paulins Kill Lake in Sussex County. Along Kittatinny Ridge in the northern part of the watershed are parts of Worthington State Forest (west), Delaware Water Gap National Recreation Area (central), and Stokes State Forests (east). In addition to these state forests, the Paulins Kill valley is host to a variety of common coniferous and deciduous trees, which have been harvested for lumber in the past, including: white oak and black oak, buttonwood, eastern red cedar, eastern hemlock, American chestnut, black walnut, tamarack larch, spruce, and pine. Trees that add to the beauty of the fall foliage include maple, birch, hickory, elm, and crab apple.