The organization is centered on its 950-acre nature reserve in Hopewell Township, Mercer County, near Pennington, which includes portions of Stony Brook, Wargo pond, over ten miles of trails, the seasonal Kate Gorrie Butterfly House,[2] and the LEED-platinum Watershed Center for Environmental Advocacy, Science, and Education.

[3] The Watershed Institute hiking trails are typically open to the public from dawn to dusk, with exceptions occurring during hunting season and days after severe weather events.

The farmstead was added to the National Register of Historic Places on September 16, 2024, for its significance in architecture and social history.

The farmhouse was once the home of Dr. Muriel Gardiner Buttinger, a noted author and psychologist, from 1940 until 1965.

The main part was built around 1830 with Greek Revival style by Andrew Drake.