Water Quality Analyses (WQA) with EPA Concurrence of MDE's Findings: Lower North Branch Patapsco River

The Patapsco LNB watershed is a free flowing stream system that is part of the Patapsco River basin of the Chesapeake Bay watershed.  The Patapsco LNB watershed drains from northwest to southeast into the tidal portion of the Patapsco River mainstem.  Upstream watersheds include Liberty Reservoir and the South Branch Patapsco River.  The watershed area of 75,756 acres is located in portions of Anne Arundel, Baltimore, Carroll, and Howard Counties, and Baltimore City.   

The Lower North Branch of the Patapsco River (Patapsco LNB) (basin code 02130906) was identified on the State’s 303(d) List as impaired by nutrients, sediments, and heavy metals (1996 listing); fecal coliform and impacts to biological communities (2002 listing); and polychlorinated biphenyls (PCBs) in fish tissue (2008 listing).  The Patapsco LNB was delisted for heavy metals in 2005, following EPA concurrence with MDE’s analysis of heavy metal data collected during 2001-2002.  The analysis showed no heavy metals impairment, except for Herbert Run where data on copper (Cu) and lead (Pb) was inconclusive.  Subsequent water quality analyses (WQAs) of Cu and Pb for Herbert Run (based on 2005-2006 data) were included as an appendix to the 2008 Integrated Report of Surface Water Quality in Maryland (Integrated Report) approved by EPA in 2008.  Upon EPA approval, the Cu and Pb impairment listings for Herbert Run were removed.  The 1996 nutrients listing was refined in the 2008 Integrated Report and phosphorus was identified as the specific impairing substance.  Consequently, for the purpose of the report available below, the terms “nutrients” and “phosphorus” will be used interchangeably.  The fecal coliform listing was addressed by a fecal bacteria TMDL submitted to EPA in 2009.  The listing for sediments will be addressed by a sediment TMDL, submitted to EPA in 2009.  The listings for PCBs in fish tissue and impacts to biological communities will be addressed separately at a future date.

Water Quality Analysis of Eutrophication for the Lower North Branch Patapsco River Basin in Anne Arundel, Baltimore, Carroll, and Howard Counties, and Baltimore City, Maryland

(Concurrence September 23, 2009)

EPA's Decision Letter

EPA's Decision Letter

Main Report

WQA_LNB_Patapsco_eutro.pdf (611KB)

Comment Response Document

CRD_LNB_Patapsco_eutro.pdf (11KB)

Additional Supporting Information

Biological Stressor Identification LNB Patapsco River Watershed Report

BSID LNB_Patapsco.pdf (726KB)

Biological Stressor Identification Methodology Report

BSID Methodology.pdf (459KB)


Contact Information

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