Water Quality Analyses (WQA) with EPA Concurrence of MDE's Findings: Potomac River Upper Tidal

The Potomac River Upper Tidal watershed is located in the central Maryland tidal region of the Potomac River.  The river segment is located in Prince George’s County and northern Charles County and extends from the Maryland – Southeast Washington, D.C. boundary downstream to Marshall Hall, MD.

Potomac River Upper Tidal (basin code 02140201) was identified on the State’s 1996 303(d) list as impaired by nutrients, suspended sediments, and copper (Cu), with additional listings of polychlorinated biphenyls (PCBs) in fish tissue in 2002, and impacts to biological communities in 2002 and 2004.  All impairments were listed for the tidal waters except for the impacts to biological communities, which are listed for non-tidal watershed tributaries.

The WQA available below establishes that the water quality criteria for Cu are being achieved in the waterbody.  Water column samples collected April 13, 2005 at five monitoring stations in the Potomac River Upper Tidal basin demonstrate that numeric water quality criteria pertaining to the designated use are being met.  Surficial sediment samples collected and used for bioassay toxicity tests demonstrate no impacts on amphipod survival or growth, therefore no sediment toxicity exists. 

Barring the receipt of any contradictory data, this report will be used to support the Cu listing change for the Potomac River Upper Tidal from Category 5 (‘waterbodies impaired by one or more pollutants and requiring a TMDL”) to Category 2 (“surface waters that are meeting some standards and have insufficient information to determine attainment of other standards”) when MDE proposes the revision of Maryland’s 303(d) list for public review in the future. 

Although the waters of the Potomac River Upper Tidal watershed do not display signs of toxic impairments due to Cu, the State reserves the right to require additional pollution controls in the Potomac River Upper Tidal watershed if evidence suggests that Cu from the basin is contributing to downstream water quality problems.  The listings for suspended sediments, nutrients, PCBs, and impacts to biological communities will be addressed separately at a future date.  

Water Quality Analysis of Copper in the Potomac River Upper Tidal, Prince George’s County and Charles County, Maryland

(EPA Concurrence: July 7, 2006)

EPA's Decision Letter EPA's Decision Letter

Main Report 

WQA_PotomacRiver_cu.pdf (898KB)

Comment Response Document

CRD_PotomacRiver_cu.pdf (57KB)

Contact Information

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