Monocacy River

Monocacy River
Monocacy River near Frederick, Maryland in 2007
The Monocacy River watershed
Native nameMonnockkesey (Shawnee)
Location
CountryUnited States
StateMaryland
CountyFrederick Carroll
Physical characteristics
Source 
  locationHarney, Carroll County, Maryland, United States
  coordinates39°43′11″N 77°13′03″W / 39.71972°N 77.21750°W / 39.71972; -77.21750
  elevation400 ft (120 m)
MouthPotomac River
  location
Dickerson, Maryland, United States
  coordinates
39°13′22″N 77°27′15″W / 39.22278°N 77.45417°W / 39.22278; -77.45417
  elevation
200 ft (61 m)
Length58 mi (93 km)
Basin size970 sq mi (2,500 km2)
Discharge 
  locationFrederick
  average1,550 cu ft/s (44 m3/s)
  minimum573 cu ft/s (16.2 m3/s)
  maximum3,060 cu ft/s (87 m3/s)
Discharge 
  locationBridgeport, Frederick
County, Maryland
  average400 cu ft/s (11 m3/s)
Basin features
Tributaries 
  leftPiney Creek, Double Pipe Creek, Israel Creek, Linganore Creek, Furnace Branch
  rightToms Creek, Tuscarora Creek, Carroll Creek, Ballenger Creek

The Monocacy River (/məˈnɒkəsi/) is a free-flowing left tributary to the Potomac River, which empties into the Atlantic Ocean via the Chesapeake Bay. The river is 58.5 miles (94.1 km) long, with a drainage area of about 970 square miles (2,500 km2). It is the largest Maryland tributary to the Potomac.

The name "Monocacy" comes from the Shawnee name for the river Monnockkesey, which translates to "river with many bends." (However, another local tradition asserts that "Monocacy" means "well-fenced garden" in an Indian language.)

The Monocacy National Battlefield lies alongside part of the river, marking an 1864 engagement during the American Civil War, the Battle of Monocacy Junction. The Chesapeake and Ohio Canal crosses over the river at the Monocacy Aqueduct, the largest of the 11 aqueducts on the canal.