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. This list of impaired waters is commonly referred to as the 303(d) List. For each WQLS, the State is required 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 Lower North Branch of the Patapsco River (Patapsco LNB) (basin code 02130906) was identified on the States 303(d) List as impaired by nutrients, sediments, and heavy metals (1996 listing); fecal coliform and impacts to biological communities (2002 listing); and polychlorinated biphenyls (PCBs) in fish tissue (2008 listing). The Patapsco LNB was delisted for heavy metals in 2005, following EPA concurrence with MDEs analysis of heavy metal data collected during 2001-2002. The analysis showed no heavy metals impairment, except for Herbert Run where data on copper (Cu) and lead (Pb) was inconclusive. Subsequent water quality analyses (WQAs) of Cu and Pb for Herbert Run (based on 2005-2006 data) were included as an appendix to the 2008 Integrated Report of Surface Water Quality in Maryland (Integrated Report) approved by EPA in 2008 (MDE 2008a). Upon EPA approval, the Cu and Pb impairment listings for Herbert Run were removed. The 1996 nutrients listing was refined in the 2008 Integrated Report and phosphorus was identified as the specific impairing substance. Consequently, for the purpose of this report the terms nutrients and phosphorus will be used interchangeably. The fecal coliform listing will be addressed by a fecal bacteria TMDL, scheduled for submittal to EPA in 2009. The listing for sediments will be addressed by a sediment TMDL, also scheduled for submittal to EPA in 2009. The listings for PCBs in fish tissue and impacts to biological communities will be addressed separately at a future date.