Final TMDLs Approved by EPA: Conococheague Creek

The Maryland 8-digit (MD 8-digit) Conococheague Creek watershed (basin number 02140504) is located in the Potomac River basin within Washington County, Maryland.  Conococheague Creek is a free flowing stream that originates in Pennsylvania and empties into the Potomac River in Maryland.  It is approximately 80 miles in length, with 22 miles in Maryland and 58 miles in Pennsylvania.  The total watershed area covers 568 square miles, with approximately 66 square miles in Maryland and 502 square miles in Pennsylvania.  Approximately 5% of the total watershed is covered by water (i.e. streams, ponds, etc.).  The total population in the MD 8-digit Conococheague Creek watershed is estimated to be approximately 21,000.

The Maryland Department of the Environment (MDE) has identified the waters of the MD 8-digit Conococheague Creek watershed on the State’s 303(d) List as impaired by sediments (1996), pH (2002), bacteria (2002), dissolved oxygen (1996), and impacts to biological communities (2004).  The designated use of the MD 8-digit Conococheague Creek and its tributaries is Use IV-P (Recreational Trout Waters and Public Water Supply). The objective of the Total Maximum Daily Load (TMDL) established in the document below is to ensure that there will be no sediment impacts affecting aquatic health, thereby establishing a sediment load that supports the Use IV-P designation for the MD 8-digit Conococheague Creek watershed. 

A TMDL for Biochemical Oxygen Demand (BOD) to address the 1996 dissolved oxygen listing was approved by the U.S. Environmental Protection Agency (EPA) in 2001, and a TMDL was submitted to the EPA in 2008 to address the 2002 bacteria listing.  The listings for pH and impacts to biological communities will be addressed separately at a future date. 


Total Maximum Daily Load of Sediment in the Conococheague Creek Watershed, Washington County, Maryland
(Approved on November 24, 2008)
EPA's Decision Letter

EPA's Decision Letter
(Revised version of letter based on MDE's edits below has not yet been posted on EPAs website)

MDE's Edits to EPA's Decision Letter MDE's Decision Letter Edits (24.4KB)
Main Report TMDL_Conococheague_Creek_final.pdf (1,218KB)
Comment Response Document CRD_Conococheague_Creek_final.pdf (7KB)

Additional Supporting Information

Using MBSS Data to Identify Stressors for Streams that Fail Biocriteria in Maryland (4775 KB)
A Methodology for Addressing Sediment Impairments in Maryland's Non-tidal Watersheds (361 KB)


Contact Information

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