Section 303(d) of the federal Clean Water Act (CWA) directs states to identify and list waters, known as water quality limited segments (WQLSs), in which current required controls of a specified substance are inadequate to achieve water quality standards. For each WQLS, the State is required to establish a Total Maximum Daily Load (TMDL) of the specified substance(s) that the waterbody can receive without violating water quality standards, demonstrate that another program or action will achieve water quality standards, or demonstrate via the development of a Water Quality Analysis (WQA) that water quality standards for the specified substance(s) are currently being achieved. The Maryland Department of the Environment (MDE) has established a WQA for sediment in the Middle Patuxent River watershed (basin code 02131106).
MDE identified the waters of the Middle Patuxent River watershed on the State’s 2008 Integrated Report of Surface Water Quality in Maryland (Integrated Report) as impaired by metals - zinc (1996), sediments (1996), and nutrients – nitrogen and phosphorus (1996). The designated use of the Middle Patuxent River mainstem and its tributaries is Use I-P (Water Contact Recreation, Protection of Aquatic Life, and Public Water Supply).
The WQA of sediment below will support a revision of the Integrated Report sediment listing for the Middle Patuxent River watershed from Category 5 (“waterbody is impaired, does not attain the water quality standard, and a TMDL is required”) to Category 2 (“waterbody is meeting some [in this case sediments-related] water quality standards, but with insufficient data to assess all impairments”), when MDE proposes the revision of the Integrated Report.
Although the waters of the Middle Patuxent River watershed do not display signs of a sediment impairment, the State reserves the right to require future controls in the watershed if evidence suggests that sediments from the basin are contributing to downstream water quality problems. A WQA for eutrophication to address the nutrients listing was approved by the EPA in 2007, and a WQA for zinc was approved by the EPA in 2009. As per the 2008 Integrated Report’s biological assessment of Maryland’s 8-digit watersheds, the Middle Patuxent River watershed was identified as supporting aquatic life.
Water Quality Analysis of Sediment in the Middle Patuxent River, Howard County, Maryland
(Concurrence December 7, 2010)
EPA's Decision Letter
EPA's Decision Letter (Does not include MDE's requested edits)
MDE's Edits to EPA's Decision Letter
MDE's Decision Letter Edits (24 KB)
Please direct questions or comments concerning this project to Maryland's TMDL Program at (410) 537-3818.
1800 Washington Boulevard, Baltimore, MD 21230