Patapsco River

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 major path of commerce; in 1723, only one ship was listed as serving the northern branch, and four others operating around the mouth.[4]

Beginning in the 1770s, the Patapsco River became the center of Maryland industrialization.[5] 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 constructed 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 inflicted heavy damage at the Bartigis Brothers plant.[6] 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 flash flood on May 27, 2018, that took the life of a 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, 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 the spot where the ship was anchored.

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.[12] 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.[12]

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

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.[19]

There is recreational swimming 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. Parts of Patapsco State Park stocked in the early spring by MD DNR, and offer some pretty decent trout fishing. The Northern Snakehead has also made the Patapsco their home. They can be found from historic Ellicott City all the way into the harbor.

This is a list of all crossings of the main stem of the Patapsco River and selected crossings of its three main tributaries. 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	$4.00 toll
	Baltimore Harbor Tunnel	I-895	Baltimore	1957	$4.00 toll
	Fort McHenry Tunnel	I-95	Baltimore	1985	$4.00 toll
	Hanover and Potee Street Bridges	MD 2	Baltimore	1973	Hanover Street Bridge reconstructed in 2005[20]
	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[21]
	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[22]
	Hammonds Ferry Road bridge	Hammonds Ferry Road	Linthicum Lansdowne	1961
	Baltimore Beltway bridge	I-695	Linthicum Lansdowne	1958	Refurbished in 1982[23]
	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[24]
	Thomas Viaduct	B&O Capital Subdivision	Elkridge Relay	1835	World's largest multiple arched bridge. Named after Philip E. Thomas[25]
	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.[26]
	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[27]
	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