This document, upon approval by the U.S. Environmental Protection Agency (EPA), establishes a Water Quality Analysis (WQA) for total phosphorus in the Lower Gunpowder Falls. 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) (MDE 2010), 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 via a Water Quality Analysis (WQA) that water quality standards are being met (CFR 2010). The Maryland Surface Water Use Designation in the Code of Maryland Regulations (COMAR) states that all surface waters of Maryland shall be protected for Use I (Water Contact Recreation, Fishing and Protection of Nontidal Warmwater Aquatic Life). In addition, within the Lower Gunpowder Falls Watershed, Long Green Run (Creek) and Sweathouse Branch, and their respective tributaries are also designated as Use III (Nontidal Coldwater Aquatic Life) (COMAR 2010a,b,c,d); and the mainstem of Gunpowder Falls (U. S. Route 95 upstream to Cromwell Bridge Road) is designated as Use IV (Recreational Trout Waters) (COMAR 2010a, b, c).