This document, upon approval by the U.S. Environmental Protection Agency (EPA), establishes a Total Maximum Daily Load (TMDL) for sediment in the Catoctin Creek watershed (basin number 02140305). Section 303(d) of the federal Clean Water Act (CWA) and the EPAs 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, the State is required to either establish a 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 Maryland Department of the Environment (MDE) has identified the waters of the Catoctin Creek watershed on the States 303(d) List as impaired by sediments (1996), nutrients (1996), bacteria (2004), and impacts to biological communities (2002 and 2006) (MDE 2007). The designated use of Catoctin Creek and its tributaries is Use IV-P (Recreational Trout Waters and Public Water Supply) (COMAR 2007a,b). A data solicitation for sediments was conducted by MDE, and all readily available data from the past five years have been considered. The listings for nutrients, bacteria, and impacts to biological communities will be addressed separately at a future date. The Catoctin Creek watershed aquatic health scores, consisting of the Benthic Index of Biotic Integrity (BIBI) and Fish Index of Biotic Integrity (FIBI), indicate that the biological metrics for the watershed exhibit a significant negative deviation from reference conditions (Roth et. al. 2005). The objective of the TMDL established herein is to ensure that there will be no sediment impacts affecting aquatic health, thereby establishing a sediment load that supports the Use IV-P designation for the Catoctin Creek watershed.