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 on the Integrated Report of Surface Water Quality in Maryland (Integrated Report), 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). Gwynns Falls (assessment unit ID: MD-02130905) was identified on the State of Marylands Integrated Report as impaired by nutrients, sediments (1996 listings), bacteria (fecal coliform), and impacts to biological communities (2002 listings). The designated uses for Gwynns Falls are as follows: Gwynns Falls and tributaries above Reisterstown Road, and Red Run and its tributaries Use III (Nontidal Cold Water); Dead Run and tributaries Use IV (Recreational Trout Waters); and all remaining waters Use I (Water Contact Recreation, and Protection of Nontidal Warmwater Aquatic Life). A TMDL was completed in 2006 to address the bacteria listing. 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. A TMDL for sediment is scheduled to be submitted to the EPA in 2009, and the listing for impacts to biological communities will be addressed separately at a future date.