Final TMDLs Approved by EPA: Double Pipe Creek

The Double Pipe Creek watershed is located within Frederick and Carroll Counties, Maryland and encompasses approximately 193 square miles.  The watershed consists of two sub-basins:  Big Pipe Creek, which makes up 58% of the total watershed area, and Little Pipe Creek, which makes up the remaining 42%.  These branches are free-flowing (non-tidal) streams that conjoin to form Double Pipe Creek.  Double Pipe Creek discharges into the Monocacy River at Rocky Ridge MD, which eventually empties into the Middle Potomac River near the town of Dickerson, MD.  The watershed is mostly rural consisting primarily of crop land and forest.  There are several minor urban areas within the basin, including Taneytown, Manchester, Union Bridge, and New Windsor, and one major urban area, the city of Westminster.

The designated use of Double Pipe Creek and its tributaries is Use I-P/Use III-P/Use IV-P (Water Contact Recreation, Protection of Nontidal Warmwater Aquatic Life, and Public Water Supply; Water Contact Recreation, Protection of Nontidal Cold Water Aquatic Life and Public Water Supply; and Water Contact Recreation, Protection of Aquatic Life, Recreational Trout Waters and Public Water Supply). 

The Maryland Department of the Environment (MDE) has identified the waters of Double Pipe Creek on the State’s Integrated Report as impaired by nutrients (1996 listing), impacts to biological communities (2002 listing), and PCB in fish tissue (2008 listing).  All impairments are listed for non-tidal streams.  Because scientific research supports that phosphorus is generally the limiting nutrient in freshwater aquatic systems, the 1996 nutrients listing was refined in the 2008 Integrated Report to identify phosphorus as the specific impairing substance.  Therefore, the listed impairment of phosphorus will henceforth be referred to in the report available below, and the term “nutrients” should be read as interchangeable with “phosphorus” in this case.  The document, available below, establishes a phosphorus TMDL for Double Pipe Creek. 

A data solicitation for nutrients was conducted by MDE in November 2009, and all readily available data from 1998 up to the time of the TMDL development have been considered.  A TMDL for sediment was approved by the US EPA in 2008, and a TMDL for fecal coliform was approved by the US EPA in 2009.  The listings for impacts to biological communities and PCB in fish tissue will be addressed separately at a future date.  

Total Maximum Daily Load of Phosphorus in the Double Pipe Creek Watershed, Frederick and Carroll Counties, Maryland

(Approved on April 26, 2013)

EPA's Decision Letter EPA's Decision Letter
(Does not include MDE's requested revisions)
MDE's Edits to EPA's Decision Letter MDE's Decision Letter Edits
Main Report Double_Pipe_Creek_NutTMDL_final.pdf (2,274KB)
Point Source Technical Memorandum Double_Pipe_Creek_Nut_PS_techmemo_final.pdf (31KB)
Nonpoint Source Technical Memorandum Double_Pipe_Creek_Nut_NPS_techmemo_final.pdf (14KB)
Comment Response Document Double_Pipe_Creek_Nut_CRD_final.pdf (23KB)

Additional Supporting Information

Biological Stressor Identification Double Pipe Creek Watershed Report Double_Pipe_BSID_Report.pdf (2,080KB)

Biological Stressor Identification Methodology 

Biological Stressor Identification Methodology (459KB)

Contact Information

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