After crossing Cross Farm Hill the road twists and turns a short distance til it reaches Lot 6 on the east side. The lot provides beach access by a boardwalk and access to Stage Island Pool, the third fresh water impoundment on the refuge. When the beach is closed most of the lot is closed, though a few spaces are kept open for pool visitors. The whole area is good for birding. 
From A Birders Guide to Parker River National Wildlife Refuge

Lot 6 is one of the six parking lots that provide access to the Parker River National Wildlife Refuge. 

Located along the northeast coast of Massachusetts, Parker River National Wildlife Refuge was established in 1941 to provide a feeding, resting, and nesting habitat for migratory birds. Most commonly associated with Plum Island, a barrier beach island, the refuge is comprised of more than 4700 acres of diverse habitats including sandy beach and dune, cranberry bog, maritime forest and shrubland, and freshwater marsh. The most abundant habitat on the refuge is its 3,000+ acres of salt marsh, one of the most productive ecosystems in nature. Parker River provides a pristine coastal habitat for over 300 species of resident and migratory birds, as well as a large variety of mammals, insects, fish, reptiles, and amphibians. The refuge also provides critical habitat for the federally threatened piping plover.

In addition to its mission of wildlife conservation, the refuge provides a variety of excellent wildlife-dependent recreational activities, including surf fishing, wildlife observation and photography, a variety of interpretive programs, and seasonal waterfowl and deer hunting opportunities. A large visitor center, complete with a classroom and auditorium, msupports many of these public uses.

Parker River has achieved the following special designations: Western Hemispheric Shorebird Reserve Network (WHSRN), Important Bird Area (IBA), and Area of Critical Environmental Concern (ACEC).