 From 1904 to 1926, Grey Towers in the borough of Milford, Pennsylvania was the site of summer field study sessions for the Master's program of the Yale School of Forestry, together with the Forester's Hall, a commercial building that was adapted and expanded for this purpose.In 1926, the Pennsylvania Power and Light Company built a hydroelectric plant on Wallenpaupack creek at the former village of Wilsonville.The town was evacuated and now lies under Lake Wallenpaupack, created by a dam.