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?

full_context: Document 1: Little Narraguagus River: The Little Narraguagus River is a short stream in Maine. From the outflow of Bear Pond ( ) in Maine Township 28, MD, Hancock County, the river runs 3.3 mi southeast and east to its confluence with the Narraguagus River in Beddington, Washington County.
Document 2: Little Saco River: The Little Saco River is a 4.5 mi tributary of the Saco River in western Maine in the United States. It begins at the junction of Haley Brook and Paine Brook in the northern part of the town of Brownfield and flows northeast, entering the town of Fryeburg just before its mouth at the Saco.
Document 3: Sullivan, Maine: Sullivan is a town in Hancock County, Maine, United States. The population was 1,236 at the 2010 census. The town was named for Daniel Sullivan, an early settler. Colloquially referred to as "Sully" or "the Sullivans" – like many Maine municipalities composed of villages with geographic designations of the town proper – the municipality was incorporated in 1789. Located in the Upper Schoodic Peninsula sub-region of Maine's Downeast Acadia region, the Municipality has had several incarnations as Waukeag, New Bristol, and later Sullivan; and once included nearby communities of Hancock, Sorrento, and what would later be (parts of Gouldsboro Point TWP, Tunk Lake TWP, the Schoodic Foothills, Hog Bay, and various other districts over time divided off) Township 7, South & Middle Districts. Once home to abundant granite quarries, the Town of Sullivan is now regarded as a residential community for nearby Ellsworth and Mount Desert Island, Maine. Located along US Rte 1, Taunton River, and Hog Bay, Sullivan is home to a slough of reversing tidal falls and many scenic turnouts that dot the Schoodic National Scenic Byway along the Upper Schoodic Peninsula.
Document 4: Little Bog River: The Little Bog River is a short stream in Hancock County, Maine. From its source ( ) in Osborn, the river runs 5.4 mi south to its confluence with Mill Brook in Eastbrook. Mill Brook flows west to Webb Pond. Via Mill Brook, Webb Pond, and Webb Brook, the Little Bog River is part of the Union River watershed.
Document 5: York, Maine: York is a town in York County, Maine, United States, near the southern tip of the state. The population in the 2010 census was 12,529. Situated beside the Atlantic Ocean on the Gulf of Maine, York is a well-known summer resort town. It is home to three 18-hole golf clubs, four sandy beaches, and Mount Agamenticus. It includes the villages of York Village, York Harbor, York Beach and Cape Neddick.
Document 6: Little Seboeis River: The Little Seboeis River is a short stream in Maine Township 4, Range 7, WELS, Penobscot County, Maine. From its source ( ), the river runs 5.5 mi south and west to its confluence with the Seboeis River.
Document 7: Little River (Presumpscot River): The Little River is an 18.8 mi tributary of the Presumpscot River in the U.S. state of Maine. It rises in the northern part of the town of Buxton in York County and flows southeast, then northeast into Gorham in Cumberland County. It flows northeast and east across Gorham, reaching the Presumpscot at the eastern boundary of the town, across from Windham.
Document 8: York County, Maine: York County is the most southwestern county of the state of Maine located along New Hampshire's eastern border in the United States. It is divided from Strafford County, New Hampshire by the
Document 9: Hampshire County, Massachusetts: Hampshire County is a historical and judicial county located in the U.S. state of Massachusetts. It has no county government. Instead there is a Hampshire Council of Governments. As of the 2010 census, the population was 158,080. Its most populous municipality is Amherst, and its county seat is Northampton. The county is named after the county Hampshire, in England.
Document 10: Lincoln County, Maine: Lincoln County is a county located in the U.S. state of Maine. As of the 2010 census, the population was 34,457. Its county seat is Wiscasset. The county was founded in 1760 from a portion of York County, Massachusetts and named after the English city Lincoln, the birthplace of Massachusetts Bay Provincial Governor Thomas Pownall.
Document 11: Baboosic Brook: Baboosic Brook is a 12.7 mi stream located in southern New Hampshire in the United States. It is a tributary of the Souhegan River, which flows to the Merrimack River and ultimately to the Gulf of Maine.
Document 12: Hancock County, Maine: Hancock County is a county located in the U.S. state of Maine. As of the 2010 census, the population was 54,418. Its county seat is Ellsworth. The county was incorporated on June 25, 1789 and named for John Hancock, the first governor of the Commonwealth of Massachusetts. The Commissioners are Antonio Blasi, Steven Joy, Percy Brown.
Document 13: Little Androscoggin River: The Little Androscoggin River is a 51.4 mi river in Maine. It flows from Bryant Pond in Woodstock ( ) to its confluence with the Androscoggin River in Auburn. The Androscoggin flows into Merrymeeting Bay in the Kennebec River estuary.
Document 14: Cumberland County, Maine: Cumberland County is a county located in the state of Maine, in the United States. As of the 2010 census, the population was 281,674, making it the most populous county in Maine. Its county seat is Portland. Cumberland County was founded in 1760 from a portion of York County, Massachusetts and named for William, Duke of Cumberland, a son of King George II.
Document 15: Little River (Salmon Falls River): The Little River is a 21.3 mi tributary of the Salmon Falls River in the U.S. state of Maine. It rises from streams in York County, flows southwest through Lebanon, and reaches its confluence with the Salmon Falls River in Berwick.
ground_truth: Hancock County