Water Quality Analysis of Eutrophication for the Little Patuxent River Basin in Anne Arundel and Howard Counties, Maryland.

摘要

Section 303(d) of the federal Clean Water Act (CWA) and the U.S. Environmental Protection Agencys (EPA) implementing regulations direct each state 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, listed in the Integrated Report of Surface Water Quality in Maryland (Integrated Report) (MDE 2008a), the State is to either establish a Total Maximum Daily Load (TMDL) of the specified substance that the waterbody can receive without violating water quality standards, or demonstrate that water quality standards are being met (CFR 2007). The Little Patuxent River watershed (assessment unit ID: MD-02131105) was identified in Marylands Integrated Report as impaired by cadmium (listed in 1996), nutrients (1996), sediment (1996), and impacts to biological communities (2006). Centennial Lake located within the watershed as identified as impaired by nutrients (1998) and sediment (1998). The Centennial Lake listings have been addressed by TMDLs approved in 2002. The cadmium listing has been addressed by a Water Quality Analyses (WQA), submitted in 2008, showing no impairment. The 1996 nutrients listing was refined in the Integrated Report by identifying phosphorus as the specific impairing substance. Consequently, for the purpose of this report the terms nutrients and phosphorus will be used interchangeably. The listings for sediment and impacts to biological communities will be addressed separately at a future date.