how did it get its name?
It was named after Colonel William Plunkett
Plunketts Creek (Loyalsock Creek tributary)
Plunketts Creek is named for Colonel William Plunkett, a physician, who was the first president judge of Northumberland County after it was formed in 1772. 
in which country is plunketts creek located? United States in which state of that country? Pennsylvania what is the length of that water body? UNANSWERABLE
wiki:21954679
Plunketts Creek (Loyalsock Creek tributary) [SEP] Name
Plunketts Creek is named for Colonel William Plunkett, a physician, who was the first president judge of Northumberland County after it was formed in 1772. During conflicts with Native Americans, he treated wounded settlers and fought the natives. Plunkett led a Pennsylvania expedition in the Pennamite–Yankee War to forcibly remove settlers from Connecticut, who had claimed and settled on lands also claimed by Pennsylvania. For his services, Plunkett was granted six tracts of land totaling on November 14, 1776, although the land was not actually surveyed until September 1783. Plunkett's land included the creek's mouth, so Plunketts Creek was given his name.