Final TMDLs Approved by EPA: Lower Monocacy River

The Monocacy River is a free flowing stream that originates in Pennsylvania and flows 58 miles within Maryland where it finally empties into the Potomac River.  The watershed covers approximately 966 square miles, with approximately 224 square miles located in Pennsylvania and 742 square miles in Maryland.  The basin can be subdivided into three distinct watersheds: the Upper Monocacy River, Lower Monocacy River, and Double Pipe Creek. 

The Maryland Department of the Environment (MDE) has identified the waters of the Lower Monocacy River on the State’s 303(d) List as impaired by sediments (1996, Lake Linganore – 1996), nutrients (1996, Lake Linganore – 1996), bacteria (2002), and impacts to biological communities (2002, 2004, and 2006). The Lower Monocacy River, upstream of US Route 40, and its tributary Israel Creek are designated as Use IV-P waterbodies (Recreational Trout Waters and Public Water Supply); Downstream of US Route 40, the Lower Monocacy River is designated as a Use I-P waterbody (Water Contact Recreation, protection of Aquatic Life, and Public Water Supply).  Additional tributaries of the Lower Monocacy River – Ballenger Creek, Bear Branch, Carroll Creek, Furnace Branch, Little Bennett Creek, and Rocky Fountain Run –are designated as Use III-P waterbodies (Non-tidal Cold Water and Public Water Supply). The Lake Linganore watershed is designated as Use IV-P.

A Total Maximum Daily Load (TMDL) for fecal coliform to address the 2002 bacteria listing was submitted to the US Environmental Protection Agency (EPA) in 2007.  A TMDL of sediments and phosphorus for the Lake Linganore impoundment was approved by the EPA in 2003.  The remaining listings for nutrients and impacts to biological communities will be addressed separately at a future date. 

Upon further review of Appendix B of the Lower Monocacy River Watershed Sediment TMDL, which was submitted to the EPA by MDE in 2008 and approved by the EPA in 2009, it was discovered that incorrect permit information (i.e., flows or concentrations) were used in the TMDL to calculate the Wasteload Allocations (WLAs) when it was originally developed.  Appendix B has been modified so as to incorporate  the correct point source information in the WLA calculations and to provide consistency with the approach applied for process water facilities within the Chesapeake Bay nutrient and sediment TMDLs.  In this modification, only the individual WLAs to the facilities included within the Process Water WLA and the manner in which this information is presented has changed; the overall Process Water WLA remains the same.  The TMDL, Load Allocation (LA), National Pollutant Discharge Elimination System (NPDES) Stormwater WLA, and NPDES Process Water WLA remain the same.  According to EPA regulation and guidance, MDE does not have to reissue the TMDL for public review for modifications such as those stated above.  The revised appendix is available below.

Total Maximum Daily Load of Sediment in the Lower Monocacy River Watershed, Frederick, Carroll, and Montgomery Counties, Maryland

(Approved on March 17, 2009)

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 (28KB)
Main Report TMDL_Lower_Monocacy_sediment_final.pdf  (1511KB)
Appendix A TMDL_LMonocacy_sediment_AppndxA.pdf (63KB)
Appendix B

TMDL_LMonocacy_sediment_Revised_AppndxB.pdf (83KB)


TMDL_LMonocacy_sediment_AppndxB.pdf (81KB)

Appendix C TMDL_LMonocacy_sediment_AppndxC.pdf (87KB)
Appendix D TMDL_LMonocacy_sediment_AppndxD.pdf (628KB)
Appendix E TMDL_LMonocacy_sediment_AppndxE.pdf (83KB)
Comment Response Document CRD_Lower Monocacy_sediment_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.