Final TMDLs Approved by EPA: Patapsco River Lower North Branch

The MD 8-digit Patapsco LNB watershed is located in the Patapsco River region of the Chesapeake Bay watershed within Maryland. The watershed covers portions of Anne Arundel, Baltimore, Carroll and Howard Counties and Baltimore City, and includes portions of the towns of Randallstown, Ellicott City, Catonsville, Arbutus, Elkridge, and Hanover. The watershed covers an area of 118.4 square miles (75,755 acres) with an additional 85.8 square miles (54,937 acres) draining from the upstream MD 8-digit South Branch Patapsco River watershed. Water draining into Liberty Reservoir typically does not drain to the Patapsco River LNB because it is retained for drinking water purposes.

The Maryland Department of the Environment (MDE) has identified the waters of the Maryland (MD) 8-digit Patapsco LNB watershed on the State’s 303(d) List [Category 5 of the Integrated Report of Surface Water Quality in Maryland (Integrated Report)] as impaired by nutrients (listed in 1996, revised in 2008 to phosphorus), sediment (1996), metals (1996), fecal bacteria (2008), impacts to biological communities (listed in 2002, 2004 and 2006), and polychlorinated biphenyls (PCBs) (2008). Herbert Run, a tributary of the Patapsco River, was listed in 2006 as impaired by lead and copper. The waters of the MD 8-digit Patapsco LNB watershed have been designated as Use I (Water Contact Recreation, and Protection of Nontidal Warmwater Aquatic Life) See Code of Maryland Regulations (COMAR) Brice Run, also a tributary of the Patapsco River, and its tributaries have been designated as Use III (Nontidal Cold Water). See COMAR

The report available below establishes a TMDL for fecal bacteria in the Patapsco River LNB watershed that will allow for attainment of the beneficial use designation of water contact recreation. The listings for phosphorus, sediment, PCBs, and impacts to biological communities will be addressed in separate TMDL documents. The listing for metals was addressed in 2002. The Herbert Run listings for lead and copper were addressed in 2008. MDE monitored the Patapsco LNB watershed from 2002-2003 for fecal bacteria. A data solicitation for fecal bacteria was conducted by MDE in 2007, and all readily available data from the past five years were considered. 

Total Maximum Daily Loads of Fecal Bacteria for the Patapsco LNB in Baltimore, Carroll, Anne Arundel, Howard Counties, and Baltimore City Maryland

(Approved on December 3, 2009)

EPA's Decision Letter

EPA's Decision Letter

Main Report

Patapsco_LNB_Bacteria_TMDL_Final.pdf (1544KB)

Comment Response Document

Patapsco_LNB_Bacteria_CRD_Final.pdf (7KB)

Contact Information

Please direct questions or comments concerning this project to Maryland's TMDL Program at (410) 537-3818.