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

The Patuxent River Upper (basin code 02131104), below Rocky Gorge Dam, extends from Howard County at the north, south through parts of Anne Arundel County and Prince George’s County flowing into the Patuxent River Middle.  The main transportation corridors in the watershed are Interstate 95 and Route 198 across the northern section, and Routes 301, 50, and 214 across the southern section of the watershed. Above Route 214 is the non-tidal portion of the Patuxent River Upper.  The drainage area of the Patuxent River Upper watershed is 88 mi2 or 56,351 acres.  Land uses in the watershed are forest (20,475 acres or 36% of the area), mixed agriculture (6,689 acres or 12%of the area), urban (22,667 acres or 40% of the area), and water (6,520 acres or 12% of the area).

The Patuxent River Upper watershed (basin code 02131104) was identified on the State’s 1996 list of WQLSs as impaired by nutrients (1996), sediments (1996) and impacts to biological communities (2002). In 2004, an impoundment within the watershed, Cash Lake, was listed as impaired for mercury. The report available below provides more recent information that supports the removal of the nutrients listing for Patuxent River Upper watershed when the 303(d) list is revised.  Other impairments within the basin will be addressed at a future date.

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

Although the waters of the Patuxent River Upper watershed do not display signs of eutrophication, the State reserves the right to require future controls in the Patuxent River Upper watershed if evidence suggests nutrients from the basin are contributing to downstream water quality problems. 

WQA of Eutrophication for the Patuxent River Upper Watershed in Anne Arundel, Prince George’s, and Howard Counties Maryland

(Concurrence February 21, 2007)

EPA's Decision Letter EPA's Decision Letter

Main Report 

WQA_pax_river_upper_eutro.pdf (477KB)

Comment Response Document

CRD_pax_river_upper_eutro.pdf (98KB)


Contact Information

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