Welkinweir is a 197-acre oasis of natural beauty located in the pastoral heart of northern Chester County. The former estate features a 55-acre arboretum, historic estate house, and ecologically diverse woodland, wetland, and meadow habitats. The property is a living laboratory for the study of ecological issues, sustainability, and land stewardship, offering inspiration and education for visitors and the local community. Welkinweir is the home of Green Valleys Watershed Association, a nonprofit with a mission to protect, preserve, and restore the natural waterways of northern Chester County.

Welkinweir was originally the home of Everett and Grace Rodebaugh, founders of the Green Valley Association. The 197 acre estate was placed by the Rodebaughs into a conservation trust and today includes an arboretum, gardens, wetlands and the mansion house. The oldest part of the mansion house was ironmaster Edwin Morris's estate where he ran a tilt hammer for a nail factory. The Green Valley Association reflects the awareness of earlier ironmasters who also understood the importance of conserving natural resources.