Patapsco River



The Patapsco River mainstem is a 39 mi 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".

History
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. 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.

Beginning in the 1770s, the Patapsco River became the center of Maryland industrialization. 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 wall of water swept the shops of Ellicott City. A 1956 flood severely damaged the Bartigis Brothers plant. 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.

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 (1798), 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.

In the early hours of March 26, 2024, the 1.6 mile Francis Scott Key Bridge, which carried Interstate 695 over the Patapsco River, was struck by a container ship and partially collapsed into the river.

Watershed
The Patapsco has a watershed (including the water surface) of 950 sqmi. Through most of its length, the Patapsco is a minor river flowing mostly through a narrow valley. The last 10 mi, 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 Patapsco River forms the harbor as it empties into the Chesapeake Bay. Besides Baltimore, the river also flows through Ellicott City (the county seat of Howard County) and Elkridge.

The Patapsco River mainstem begins at the confluence of the North and South Branches, near Marriottsville, about 15 mi west of downtown Baltimore. The 19.4 mi South Branch rises further west at Parr's Spring, where Howard County, Carroll, Frederick, and Montgomery counties meet. The latter begins at elevation 780 ft on Parr's Ridge, just south of Interstate 70 and east of Ridge Road (Highway 27), 2 mi south of Mount Airy, Maryland. The South Branch Patapsco River traces the southern boundary of Carroll County and the northern boundary of Howard County. The first land record regarding Parr's Springs dates from 1744, when John Parr laid out a 200 acre 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. Parr's Spring was dug to form a 1.75 acre pond in the 1950s, filled by seven spring heads that form the headwaters of the South Branch of the Patapsco River.

The North Branch flows 20.9 mi 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.

Patapsco Valley State Park extends along 32 mi of the Patapsco and its branches, encompassing 14000 acre 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. Bloede's Dam, a hydroelectric dam built in 1906, was on the Patapsco River within the 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. 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. Dam demolition began on September 12, 2018, opening the fishery and creating a rocky rapid for kayaking. Two dams upstream of Bloede's Dam, Simkins and Union, were removed in 2010. The removal of Bloede's Dam leaves Daniels Dam, 9 mi upstream, as the last remaining dam along the mainstem Patapsco River.

Tributaries

 * Deep Run (Carroll County)
 * Board Run (Baltimore County)
 * Roaring Run (Carroll County)
 * Liberty Reservoir (Carroll/Baltimore Counties)
 * Piney Run (Carroll County)
 * 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)

Ecology and conservation
The removal of Bloede's Dam in September 2018, opened up 65 mi 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. 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.

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 mi of Patapsco River mainstem, the entire 19.4 mi length of the South Branch Patapsco River, 3.5 mi of the North Branch Patapsco River up to the Liberty Dam, and many of these rivers' tributaries.

Water quality
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. The Piney Run Reservoir on the South Branch of the Patapsco is polluted by excess levels of phosphorus and sediment.

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.

Recreation
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.

Crossings
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.