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

The Potomac River Lower North Branch (LNB) watershed is located in the North Branch Potomac River sub-basin within Maryland (02-14-10).  The North Branch of the Potomac River delineates the border between Maryland and West Virginia from its origin at the Fairfax Stone in West Virginia to its confluence with the South Branch of the Potomac near Oldtown, Maryland.  The Lower North Branch is defined as the reach extending from the Savage River to the confluence with the South Branch Potomac River.  Its land area is segmented by the watersheds of Wills Creek and Evitts Creek, which enter the LNB in Cumberland (Figure 1).  The watershed covers 73,144 acres in Allegany County, Maryland.

The Potomac River LNB watershed (basin code 02141001), located in Allegany County, was identified on the 2008 Integrated Report under Category 5 as impaired by nutrients and sediment (1996 listings), methyl mercury, and impacts to biological communities (2002 listings). 

The report available below provides an analysis of recent monitoring data to address whether or not the watershed is still impaired by nutrients. The study demonstrates that both applicable criteria for nutrients and the designated uses supported by this criteria are being met in the Potomac River LNB 8-digit basin; therefore, a nutrient TMDL is not required.

Although the waters of the Potomac River LNB do not display signs of eutrophication, the State reserves the right to require future controls in the Potomac River LNB watershed if evidence suggests nutrients from the basin are contributing to downstream water quality problems. Other substances not addressed at this time, but identified on Maryland’s 303(d) list as impairing the Potomac River LNB 8-digit basin, will be addressed in the future. 

WQA of Eutrophication for Potomac River LNB, Allegany County, Maryland

(EPA Concurrence: May 18, 2012)

EPA's Decision Letter EPA's Decision Letter

Main Report 

Potomac_LNB_Nut_WQA_5-31-11_final.pdf (748KB)

Comment Response Document

Potomac_LNB_Nut_CRD_final.pdf (7KB)           

Contact Information

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