Patapsco River

Patapsco River The River of History
Patapsco Valley State Park at Catonsville
Patapsco River Watershed
Native name	Potapskut (Algonquian languages)
Location
Country	United States
State	Maryland
Region	Baltimore metropolitan area, Patapsco Valley
Cities	Baltimore, Elkridge, Ellicott City
Physical characteristics
Source
• location	Marriottsville
• coordinates	39°20′59″N 76°52′56″W / 39.3498272°N 76.8821987°W / 39.3498272; -76.8821987
• elevation	260 ft (79 m)
Mouth	Chesapeake Bay
• location	Baltimore
• coordinates	39°10′25″N 76°26′36″W / 39.1737202°N 76.4432935°W / 39.1737202; -76.4432935
• elevation	0 ft (0 m)
Length	63 км
Basin size	950 sq mi (2,460 km2)
Basin features
Tributaries
• left	North Branch
• right	South Branch

The Patapsco River (/pəˈtæpˌskoʊ/ pə-TAP-skoh ^ⓘ) mainstem is a 39-mile (63 km)^[1] river in central Maryland that 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]

Captain John Smith was the first European to explore the river, noting it on his 1612 map as the Bolus River. The "Red river", named after the clay color, is considered the "old Bolus", as other branches were also labeled Bolus on maps.^[3] As the river was not navigable beyond Elkridge, it was not a significant path of commerce; in 1723, only one ship was listed as serving the northern branch, and four others operating around the mouth.^[4]

The first land record regarding Parr's Springs, the source of the South Branch, dates from 1744, when John Parr laid out a 200 acres (81 ha) tract he called Parr's Range. During the Civil War, Parr's Spring was a stop for the Army of the Potomac's Brig. Gen. David M. Gregg's cavalry, on June 29, 1863, while en route to Gettysburg, Pennsylvania.^[5] Parr's Spring was dug to form a 1.75 acres (7,100 m²) pond in the 1950s, filled by seven spring heads that form the headwaters of the South Branch of the Patapsco River.^[6]

Beginning in the 1770s, the Patapsco River became the center of Maryland industrialization.^[7] Milling and manufacturing operations abounded along the river throughout the eighteenth and nineteenth centuries, generally powered by small dams. The Baltimore and Ohio Railroad's original main line was constructed in 1829 west along the Patapsco Valley; the nation's first railroad, the route remains, though much altered. Many railroad bridges were built in the valley, including the Thomas Viaduct, which is still in use, and the Patterson Viaduct, now in ruins. The 1907 hydropower Bloede's Dam powered flour mills.

An 1868 flood washed away 14 houses and killed 39 people around Ellicott City. A 1923 flood topped bridges. In 1952, an 8 ft (2.4 m) wall of water swept the shops of Ellicott City. A 1956 flood severely damaged the Bartigis Brothers plant.^[8] In 1972, rainfall from the remnants of Hurricane Agnes damaged Ellicott City and the Old Main Line. Two died in the July 2016 Maryland flood ravaged Main Street, followed two years later by a May 2018 Maryland flood that took the life of a rescuer.^[9]

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, aboard the British HMS Tonnant, 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 where the ship was anchored.

Bloede's Dam, a hydroelectric dam built in 1906, was on the Patapsco River within Patapsco Valley State Park, a nearly complete barrier to anadromous fish passage. Although a fish ladder was installed in 1992, it blocked five of six native fish species trying to run upstream to spawn.^[10] Efforts to remove Bloede's Dam began in the 1980s when nine drowning deaths occurred, and also to restore fish passage to a large portion of the Patapsco River watershed.^[11][12] Dam demolition began on September 12, 2018, opening the fishery and creating a rocky rapid for kayaking.^[13] Two dams upstream of Bloede's Dam, Simkins and Union, were removed in 2010.^[14][15] The removal of Bloede's Dam leaves Daniels Dam, 9 miles (14 km) upstream, as the last remaining dam along the mainstem Patapsco River.^[10]

In the early hours of March 26, 2024, the 1.6-mile-long (2.6 km) Francis Scott Key Bridge, which carried Interstate 695 over the Patapsco River, was struck by a container ship and partially collapsed into the river.^[16]

The 19.4-mile-long (31.2 km)^[1] South Branch rises at Parr's Spring, where Howard County, Carroll, Frederick, and Montgomery counties meet. The latter begins at elevation 780 feet (240 m) on Parr's Ridge, just south of Interstate 70 and east of Ridge Road (Highway 27), 2 miles (3 km) south of Mount Airy, Maryland.^[1] The South Branch Patapsco River traces the southern boundary of Carroll County and the northern boundary of Howard County.

The North Branch flows 20.9 miles (33.6 km)^[1] southward from its origins in Carroll County. Liberty Dam and its reservoir on the North Branch are major components of the Baltimore City water system.^[17]

The Patapsco River mainstem begins at the confluence of the North and South Branches, near Marriottsville, about 15 miles (24 km) west of downtown Baltimore. Through most of its length, the Patapsco is a minor river flowing mostly through a narrow valley. Patapsco Valley State Park extends along 32 miles (51 km) of the Patapsco and its branches, encompassing 14,000 acres (5,700 ha) in five areas. The river cuts a gorge 100 to 200 feet (35–70 m) deep within the park, with rocky cliffs and tributary waterfalls.

The last 10 miles (16 km), form a large tidal estuary inlet of Chesapeake Bay. Two lobes of the harbor deviate from the "mainstem" harbor: the Middle Branch Patapsco River, into which Gwynns Falls; and the Northwest Branch Patapsco River, into which Jones Falls flows. The inner part of this estuary provides the harbor of Baltimore. Thoms Cove is further down the main harbor. The Patapsco estuary is south of the Back River and north of the Magothy River.

The Patapsco has a watershed (including the water surface) of 950 square miles (2,460 km²).^[15]

The removal of Bloede's Dam in September 2018, opened up 65 miles (105 km) of the Patapsco River watershed, which will potentially restore spawning runs of at least six species of native anadromous fish: alewife (Alosa pseudoharengus), blueback herring (Alosa aestivalis), American shad (Alosa sapidissima), hickory shad (Alosa mediocris), striped bass (Morone saxatilis), sea lamprey (Petromyzon marinus), as only one species, sea lamprey, were found using the Bloede's Dam fish ladder in 2012.^[10] One catadromous species would likely also benefit, the American eel (Anguilla rostrata), a fish species that lives in freshwater and migrates to the ocean to breed. The Bloede's Dam removal project was led by American Rivers and the Maryland Department of Natural Resources.^[10]

Now that Bloede's Dam has been removed, removal of Daniels Dam upstream on the mainstem Patapsco River would open to anadromous fishes the remaining 6.5 miles (10.5 km) of Patapsco River mainstem, the entire 19.4 miles (31.2 km) length of the South Branch Patapsco River, 3.5 miles (5.6 km) of the North Branch Patapsco River up to the Liberty Dam, and many of these rivers' tributaries.^[1]

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.^[18] The Piney Run Reservoir on the South Branch of the Patapsco is polluted by excess levels of phosphorus and sediment.^[19]

Environmental nonprofit organizations, such as The Friends of Patapsco Valley & Heritage Greenway, Inc. (PHG), lead clean-up efforts by the residents of surrounding communities. 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.^[20]

Recreational swimming is possible in areas of the Patapsco River, sometimes involving rope swings, inner tubing, and wading. The river also serves as a venue for rafting. The Patapsco is also great for fishing. The MD DNR stocks parts of Patapsco State Park in the early spring and offers some pretty decent trout fishing. The Northern Snakehead has also made the Patapsco their home. They can be found from historic Ellicott City to the harbor.

This is a list of all crossings of the main stem of the Patapsco River, as well as its two downstream short branches, the Middle Branch and Northwest Branch. Listings start downstream and continue upstream to the sources of the rivers.

Image	Crossing	Carries	Location	Opened	Notes
Anne Arundel County – Baltimore County
	Francis Scott Key Bridge	I-695	Baltimore	1977–2024	Collapsed after being struck by a container ship on March 26, 2024
	Baltimore Harbor Tunnel	I-895	Baltimore	1957	$4.00 toll
	Fort McHenry Tunnel	I-95	Baltimore	1985	Crosses Northwest Branch only; $4.00 toll
	Hanover Bridge	MD 2	Baltimore		Crosses Middle Branch only
	Spring Garden Swing Bridge	Western Maryland Railway	Baltimore	1904[21]	Crosses Middle Branch only
	Ridgleys Cove interchange	I-95 I-395	Baltimore		Crosses Middle Branch only
	Light rail bridge	Baltimore Light RailLink	Baltimore		Crosses Middle Branch only
	Hanover and Potee Street Bridges	MD 2	Baltimore	1973	Hanover Street Bridge reconstructed in 2005[22]
	Curtis Bay Branch Railroad bridge	B&O Curtis Bay Branch	Baltimore
	Patapsco Avenue bridge	Patapsco Avenue	Brooklyn, Baltimore	1961
	I-895 bridge near South West Area Park	I-895	Baltimore Highlands	1958	Refurbished in 2019[23]
	Central Light Rail bridge	Baltimore Light Rail	Baltimore Highlands	1908	Previously used for the Baltimore and Annapolis Railroad
	Old Annapolis Road bridge	MD 648	Baltimore Highlands
	BW Parkway bridge	MD 295	Baltimore Highlands	1948	Refurbished in 1985[24]
	Hammonds Ferry Road bridge	Hammonds Ferry Road	Linthicum Lansdowne	1961
	Baltimore Beltway bridge	I-695	Linthicum Lansdowne	1958	Refurbished in 1982[25]
	Northeast Corridor bridge	Amtrak Northeast Corridor	Linthicum Halethorpe
	I-195 bridge	I-195	Elkridge Halethorpe	1988
Howard County – Baltimore County
	I-895 bridge	I-895	Elkridge Relay	1973	On/off ramp bridges flank US 1 bridge to north and south
	Patapsco River Bridge	US 1	Elkridge Relay	1915	Concrete arch bridge refurbished in 1952[26]
	Thomas Viaduct	B&O Capital Subdivision	Elkridge Relay	1835	World's largest multiple arched bridge. Named after Philip E. Thomas.[27]
	I-95 bridge	I-95	Elkridge Relay	1968
	Gun Road bridge	Gun Road	Relay		Patapsco Valley State Park access only
	Patapsco Swinging Bridge	Swinging Bridge Trail	Ilchester	2006	Pedestrian bridge connecting River Road to Grist Mill Trail
	Patterson Viaduct	Grist Mill Trail	Ilchester	2006	Former rail bridge opened 1829, destroyed 1868, and rebuilt 1869; new footbridge built on abutments of prior rail bridge
	Ilchester Bridge	Old Main Line Subdivision	Ilchester	1903
	Ilchester Road bridge	Ilchester Road	Ilchester		Known as Heartbeat Bridge in local folklore.[28]
	Main Street Bridge	MD 144	Ellicott City Oella	1914
	Baltimore National Pike Bridge	US 40	Ellicott City Catonsville	1936	Reconstructed using original arches in 2014[29]
	I-70 bridge	I-70	Ellicott City Catonsville	1966
	Hollifield Bridge	Old Frederick Road	Daniels	1934
	Daniels bridge	Old Main Line Subdivision	Daniels
	Eureka bridge	Old Main Line Subdivision	Mt. Airy
	MD 125 bridge	MD 125	Woodstock	1981
Patapsco River North Branch-South Branch confluence

• Patapsco Vallis, a valley on Mars named after the river in Maryland
• Bloede's Dam
• List of Maryland rivers
• List of parks in the Baltimore–Washington metropolitan area
• Liberty Reservoir

Wikimedia Commons has media related to Patapsco River.

• Maryland DNR's Surf Your Watershed: Patapsco/Back River
• American Rivers, a nonprofit conservation organization
• Maryland Port Administration
• Blue Water Baltimore, formed in 2010 from a merger of the Gwynns Falls, Jones Falls, Herring Run, and Baltimore Harbor Watershed associations, and the Baltimore Harbor Waterkeeper
• Patapsco Heritage Greenway
• Patapsco River Rock Building