Patapsco River

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Patapsco River (Potapskut)
Patapsco fg01.jpg
Country United States
State Maryland
Region Baltimore metropolitan area, Patapsco Valley
 - left North Branch
 - right South Branch
Cities Baltimore, Elkridge, Ellicott City
 - location Marriottsville
 - elevation 260 ft (79 m)
 - coordinates 39°20′59″N 76°52′56″W / 39.3498272°N 76.8821987°W / 39.3498272; -76.8821987
Mouth Chesapeake Bay
 - location Baltimore
 - elevation 0 ft (0 m)
 - coordinates 39°10′25″N 76°26′36″W / 39.1737202°N 76.4432935°W / 39.1737202; -76.4432935Coordinates: 39°10′25″N 76°26′36″W / 39.1737202°N 76.4432935°W / 39.1737202; -76.4432935
Basin 632 sq mi (1,637 km2)
Patapscomap (cropped).png
Patapsco River Watershed

The Patapsco River is a 39-mile-long (63 km)[1] river in central Maryland which flows into the Chesapeake Bay. The river's tidal portion forms the harbor for the city of Baltimore. With its South Branch, the Patapsco forms the northern border of Howard County, Maryland. The name "Patapsco" is derived from the Algonquian pota-psk-ut, which translates to "backwater" or "tide covered with froth."[2]


The Patapsco proper begins at the confluence of the North and South Branches, near Marriottsville, approximately 15 miles (24 km) west of downtown Baltimore. The 19.4-mile-long (31.2 km)[1] South Branch rises further west at Parrs Spring, where Howard County, Carroll, Frederick, and Montgomery counties meet. The North Branch flows 20.9 miles (33.6 km)[1] southward from its origins in Carroll County. Through most of its length, the Patapsco is a minor river, flowing for the most part through a narrow valley. The last 10 miles (16 km), however, form a large tidal estuary inlet of Chesapeake Bay. The inner part of this estuary provides the harbor of Baltimore, composed of the Northwest Harbor and the Middle Branch including Thoms Cove. (See Baltimore Inner Harbor.) The Patapsco estuary is south of the Back River and north of the Magothy River.

The Inner Harbor from the Baltimore Aquarium. The Patapsco River forms the harbor as it empties into the Chesapeake Bay.

The Patapsco has a watershed area (including the water surface) of 680 square miles (1,760 km2), or 632 square miles (1,637 km2) of land. Thus, its total watershed area is 7% water.[citation needed]

Patapsco Valley State Park is adjacent to 32 miles (51 km) of the Patapsco and its branches, encompassing a total of 14,000 acres (5,700 ha) in five different areas. The river cuts a gorge 100–200 feet (35–70 m) deep within the park, which features rocky cliffs and tributary waterfalls.

Liberty Dam and its reservoir, located on the North Branch, is a major component of the Baltimore city water system.[3] Besides Baltimore, the river also flows through Ellicott City (the county seat of Howard County) and Elkridge.


John Smith was the first European to explore the river noting it on his 1612 map as the Bolus River. The "Red river", was named after the clay color, and is considered the "old Bolus", as other branches were also labelled Bolus on maps.[4] As the river was not navigable beyond Elkridge, it was not a major path of commerce with only one ship listed as serving the northern branch, and four others operating around the mouth in 1723.[5] The Patapsco valley was used as the route of the Baltimore and Ohio Railroad's original main line west constructed from 1829 onwards, and this route remains, though much altered. Many old railroad bridges were constructed in the valley, most notably the Thomas Viaduct and the Patterson Viaduct, of which ruins remain. Flour mills and a hydropower dam were formerly powered by the river.

The valley is prone to periodic flooding. Modern floods include the 1868 flood that washed away 14 houses and killed 39 people around Ellicott City. A 1923 flood topped bridges while in 1952, an eight-foot wall of water swept the shops of Ellicott City. A 1956 flood inflicted heavy damage at the Bartigis Brothers plant.[6] In 1972, as a result of rainfall from the remnants of Hurricane Agnes, Ellicott City and the Old Main Line sustained serious damage. The July 2016 Maryland flood ravaged Main Street leaving two dead, followed just two years later by a flash flood on May 27, 2018 that took the life of one rescuer.[7]

The mouth of the Patapsco River forms Baltimore harbor, the site of the Battle of Baltimore during the War of 1812. This is where Francis Scott Key, while aboard a British ship, wrote "The Star-Spangled Banner," a poem later set to music as the national anthem of the United States. Today, a red, white, and blue buoy marks the spot where HMS Tonnant was anchored.


  • Deep Run (Carroll County)
  • Board Run (Baltimore County)
  • Roaring Run (Carroll County)
  • Liberty Reservoir (Carroll/Baltimore Counties)
  • Keysers Run (Baltimore County)
  • Beaver Run (Carroll County)
  • Norris Run (Baltimore County)
  • Timber Run (Baltimore County)
  • Middle Run (Carroll County)
  • Morgan Run (Carroll County)
  • Locust Run (Baltimore County)
  • Snowdens Run (Carroll County)
  • Falls Run (Baltimore County)
  • South Branch Patapsco River
  • Davis Branch (Howard County)
  • Brice Run (Baltimore County)
  • Bens Run (Baltimore County)
  • Cedar Branch (Baltimore County)
  • Miller Run (Baltimore County)
  • Sucker Branch (Howard County)
  • Tiber River (Howard County)
  • Cooper Branch (Baltimore County)
  • Bonnie Branch (Howard County)
  • Sawmill Branch (Baltimore County)
  • Cascade Falls (Howard County)
  • Soapstone Branch (Baltimore County)
  • Rockburn Branch (Howard County)
  • Deep Run (Howard/Anne Arundel County)
  • Stony Run (Anne Arundel County)
  • Herbert Run (Baltimore County)
  • Holly Creek (Anne Arundel County)
  • Middle Branch to Gwynns Falls (Baltimore City)
  • Northwest Harbor to Jones Falls (Baltimore City)
  • Colgate Creek (Baltimore City)
  • Curtis Creek (Baltimore City)
  • Bear Creek (Baltimore County)
  • Cox Creek (Anne Arundel County)
  • Stoney Creek (Anne Arundel County)
  • Rock Creek (Anne Arundel County)
  • Old Road Bay (Baltimore County)
  • Bodkin Creek (Anne Arundel County)

Water quality[edit]

Volunteers at a community cleanup of Herbert Run, a tributary of the Patapsco River running through Arbutus, Maryland

The eastern portion of the Patapsco River is in a highly urbanized area and is subject to extensive stormwater runoff and other forms of water pollution. The Maryland Department of the Environment has identified the Lower North Branch as containing high levels of heavy metals (chromium, arsenic, cadmium, copper, mercury, nickel, lead, selenium, and zinc), as well as phosphorus, fecal coliform bacteria, and PCBs.[8]

Clean-up efforts by the residents of surrounding communities have been led by environmental nonprofit organizations, such as The Friends of Patapsco Valley & Heritage Greenway, Inc. (PHG). From 2006 to 2012, PHG volunteers participated in 183 stream clean ups, removing 264 tons of trash from the streams of the Patapsco Valley watershed.[9]


Teenagers enjoy swimming in areas of the Patapsco River, typically including rope swings, inner tubing, and wading. The river also serves as a venue for rafting.


Crossing Carries Location
Howard County - Baltimore County
MD 125 bridge MD 125 (Old Court Road) Woodstock
Eureka bridge B&O Old Main Line Subdivision Mt. Airy
Daniels bridge B&O Old Main Line Subdivision Daniels
Hollifield Bridge Old Frederick Road Daniels
I-70 bridge I-70 Ellicott City
Baltimore National Pike Bridge US 40 (Baltimore National Pike) Ellicott City
Main Street Bridge MD 144 (Main Street) Ellicott City
Ilchester Road bridge Ilchester Road Ilchester
Ilchester Bridge B&O Old Main Line Subdivision Ilchester
Grist Mill Trail Bridge Grist Mill Trail Ilchester
Patapsco Swinging Bridge Patapsco Swinging Bridge Trail Ilchester
Gun Road bridge Gun Road Relay
I-95 bridge I-95 Elkridge
Thomas Viaduct B&O Capital Subdivision Elkridge
US 1 bridge US 1 (Washington Boulevard) Elkridge
I-895 bridge I-895 (Harbor Tunnel Thruway) Elkridge
Anne Arundel County – Baltimore County
I-195 bridge I-195 (Metropolitan Boulevard)) Elkridge
Northeast Corridor bridge Amtrak Northeast Corridor Linthicum
Baltimore Beltway bridge I-695 (Baltimore Beltway) Linthicum
Hammonds Ferry Road bridge Hammonds Ferry Road Linthicum
BW Parkway bridge MD 295 (Baltimore-Washington Parkway) Baltimore Highlands
MD 648 bridge MD 648 (Baltimore-Annapolis Boulevard) Baltimore Highlands
Central Light Rail bridge Baltimore Light Rail Baltimore Highlands
I-895 bridge near South West Area Park I-895 (Harbor Tunnel Thruway) Baltimore Highlands
Patapsco Avenue bridge Patapsco Avenue Brooklyn, Baltimore
Curtis Bay Branch Railroad bridge B&O Curtis Bay Branch Baltimore
Hanover & Potee Streets bridge MD 2 (Hanover Street-Potee Street) Baltimore
Fort McHenry Tunnel I-95 Baltimore
Baltimore Harbor Tunnel I-895 (Harbor Tunnel Thruway) Baltimore
Francis Scott Key Bridge I-695 (Baltimore Beltway) Baltimore

See also[edit]


  1. ^ a b c U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map Archived 2012-04-05 at WebCite, accessed April 1, 2011
  2. ^ "Ghosts of industrial heyday still haunt Baltimore's harbor, creeks". Chesapeake Bay Journal. Retrieved 2012-09-08. 
  3. ^ Baltimore County Department of Environmental Protection and Resource Management. Towson, MD. "Patapsco River Watershed." 2009-07-13.
  4. ^ John Thomas Scharf. The Chronicles of Baltimore: Being a Complete History of Baltimore Town. p. 8. 
  5. ^ John Thomas Scharf. The Chronicles of Baltimore: Being a Complete History of Baltimore Town. p. 18. 
  6. ^ "The Patapsco River Creator-Destroyer". The Times (Ellicott City). 31 March 1965. 
  7. ^
  8. ^ Maryland Department of the Environment. Baltimore, MD (2009). "Notice of Intent to Establish Total Maximum Daily Load (TMDL) of Sediment: Patapsco River Lower North Branch Watershed."[dead link]
  9. ^ "Protecting the Valley". Friends of Patapsco Valley & Heritage Greenway, Inc. Retrieved May 24, 2012. 

External links[edit]