Ridley Creek is a tributary of the Delaware River in Chester and Delaware counties, Pennsylvania in the United States. The entire drainage basin is in the suburban Philadelphia area, but the upper creek and extensive park lands on the creek retain a rural character, while the mouth of the creek has long been heavily industrialized. Its watershed is considered to h…Ridley Creek is a tributary of the Delaware River in Chester and Delaware counties, Pennsylvania in the United States. The entire drainage basin is in the suburban Philadelphia area, but the upper creek and extensive park lands on the creek retain a rural character, while the mouth of the creek has long been heavily industrialized. Its watershed is considered to have the highest quality water in Delaware County. The creek was named for the parish of Ridley, Cheshire, England.