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 8-Digit (MD 8-digit) Upper Monocacy River watershed (basin code 02140303) is located within Frederick and Carroll Counties, Maryland. It lies to the west of the Town of Westminster. The Upper Monocacy River and its tributaries flow through several small towns, including Thurmont, Taneytown, and Emmitsburg. The total Upper Monocacy River watershed spans 472 square miles, with 5% of the total watershed area covered by water (i.e., streams, ponds, etc.).
The Maryland Department of the Environment (MDE) has identified the waters of the MD 8-digit Upper Monocacy River watershed on the State’s 303(d) List as impaired by sediments (1996), nutrients (1996), bacteria (2002), and impacts to biological communities (2002, 2004, and 2006). The designated use of the MD 8-digit Upper Monocacy River and its tributaries is Use IV-P (Recreational Trout Waters and Public Water Supply) except for Fishing Creek, Hunting Creek, Owens Creek, and Friends Creek, which are designated as Use III-P (Nontidal Cold Water and Public Water Supply). The objective of the Total Maximum Daily Load (TMDL) established 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/III-P designations for the MD 8-digit Upper Monocacy River watershed.
A data solicitation for sediments was conducted by MDE, and all readily available data from the past five years have been considered. A TMDL for fecal bacteria was submitted to the US Environmental Protection Agency (EPA) in 2007. The listings for nutrients and impacts to biological communities will be addressed separately at a future date.
Upon further review of Appendix B of the Upper 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.
On April 9, 2013, in conjunction with the renewal of the White Rock WWTP permit renewal (NPDES# MD0025089), updates were made to Appendix B of the Total Maximum Daily Load (TMDL) of Sediment in the Upper Monocacy River Watershed, Frederick and Carroll Counties, Maryland. Two facilities with permits regulating their discharges are being added which were inadvertently left out of the original TMDL due to incorrect location information, but have since been verified to geographically lie within the watershed. Two facilities with permits regulating their discharges have been removed from the TMDL as operations have ceased since the original TMDL was established. Appendix B has been modified so as to incorporate the correct point source information in the WLA calculations.
In this modification, only the facilities included in the aggregate Process Water WLA have 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 B is available below.
(Approved on December 3, 2009)
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)
Please direct questions or comments concerning this project to Maryland's TMDL Program at (410) 537-3818.
1800 Washington Boulevard, Baltimore, MD 21230