Water Quality Analysis of Eutrophication for the Wills Creek Basin in Alleghany and Garrett 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 2009). The Wills Creek watershed (basin code 02141003) (2008 Integrated Report Assessment Unit ID: MD-02141003) was identified in Marylands 2008 Integrated Report as impaired by cyanide (1996 listing), nutrients (1996 listing), sediment (1996 listing), pH (1998, 2002, 2004 and 2006 listings), fecal bacteria (2002 listing), and impacts to biological communities (2002 listing) (MDE 2008a). The listing for cyanide and the 1998 and 2004 pH listings have been addressed by Water Quality Analyses (WQAs) completed in 2005 and 2006, respectively, showing no impairment. The listings for sediment and fecal bacteria have been addressed via TMDLs completed in 2006, and the 2002 and 2006 pH listings were addressed via TMDLs completed in 2008. The 1996 nutrients listing was refined in the 2008 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 impacts to biological communities will be addressed separately at a future date.