The Antietam Creek watershed is located in the Potomac River sub-basin within Washington County, Maryland. Antietam Creek is a free-flowing stream that originates in Pennsylvania and empties into the Potomac River in Maryland downstream of Shepherdstown, WV; but upstream from Harpers Ferry, WV. It is approximately 54 miles in length, with 37 miles in Maryland and 17 miles in Pennsylvania. The total watershed area covers 186,203 acres, with approximately 118,667 acres in Maryland and 67,536 acres in Pennsylvania.
The designated use of Antietam Creek and its tributaries is Use IV-P (Water Contact Recreation, Protection of Aquatic Life, Recreational Trout Waters and Public Water Supply) except for Beaver Creek, Marsh Run, and Little Antietam Creek, which are classified as Use III-P (Water Contact Recreation and Protection of Nontidal Cold Water Aquatic Life, and Public Water Supply).
The Maryland Department of the Environment (MDE) has identified the waters of Antietam Creek on the State’s 2010 Integrated Report as impaired by nutrients (1996), impacts to biological communities (2002), and PCB in fish tissue (2008). Because scientific research supports that phosphorus is generally the limiting nutrient in freshwater aquatic systems, the 1996 nutrients listing was refined in Maryland’s 2008 Integrated Report to identify phosphorus as the specific impairing nutrient substance. Therefore, the listed impairment of phosphorus will henceforth be referred to in this report and the term “nutrients” should be read as interchangeable with “phosphorus” in this case.
Once approved by EPA, the document, available below, establishes a TMDL for Nutrients (Phosphorus) in the Antietam Creek watershed. A data solicitation for nutrients was conducted by MDE in November 2009, and all readily available data up to the time of the TMDL development have been considered. A TMDL for carbonaceous biochemical oxygen demand (CBOD) and nitrogenous biochemical oxygen demand (NBOD) was approved by the EPA in 2002. A Water Quality Analysis (WQA) of eutrophication for the Greenbrier Lake impoundment was approved by the EPA in 2005. A TMDL for sediment was approved by EPA in 2008, and a TMDL for bacteria was approved by 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 Antietam Creek Watershed, Washington County, Maryland (Approved on September 25, 2013)
Additional Supporting Information
Biological Stressor Identification Methodology
Biological Stressor Identification Methodology (459KB)
Please direct questions or comments concerning this project to Maryland's TMDL Program at (410) 537-3818.
1800 Washington Boulevard, Baltimore, MD 21230