This document, upon approval by the U.S. Environmental Protection Agency (EPA), establishes a Total Maximum Daily Load (TMDL) for sediment in the Cabin John Creek watershed (basin number 02140207) (2010 Integrated Report of Surface Water Quality in Maryland Assessment Unit ID: MD-02140207). 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 2009b). The Maryland Department of the Environment (MDE) has identified the waters of the Cabin John Creek watershed on the States 2010 Integrated Report as impaired by sediments (1996), nutrients phosphorus (1996), bacteria (2002), chlorides (2010), sulfates (2010), and impacts to biological communities (2006) (MDE 2010b). The designated use of the Cabin John Creek mainstem and its tributaries is Use I-P (Water Contact Recreation, Protection of Aquatic Life, and Public Water Supply) (COMAR 2009a,b).