Question: What County that was incorporated on June 25, 1789 and named for John Hancock, has a short stream  from its source the river runs 5.4 mi south to its confluence with Mill Brook in Eastbrook?
Sentence (from "Spring River (Maine)"): From the outflow of Narraguagus Lake ( ), the river runs 4.0 mi northeast to its confluence with the West Branch Narraguagus River.
Relevant evidence: No