Upon approval by the U.S. Environmental Protection Agency (EPA) this document will establish Total Maximum Daily Loads for nitrogen and phosphorus in the Patapsco River Mesohaline Stream Segment PATMH (not including Bodkin Creek). Hereafter this stream segment will be referred to as the Baltimore Harbor or the Harbor (basin number 02130903). The Baltimore Harbor drains into the Chesapeake Bay and is part of the Patapsco/Back River Tributary Strategy Basin. Baltimore Harbor (basin number 02130903) was identified on the States 1996 list of water quality limited segments (WQLSs) submitted to the U.S. EPA by the Maryland Department of the Environment (MDE) as impaired by nutrients. The Baltimore Harbor has also been identified on the 303(d) list as impaired by bacteria (fecal coliform) (1998), toxics (polychlorinated biphenyls, or PCBs) (1998), metals (chromium, zinc and lead) (1998), suspended sediments (1996), and impacts to biological communities (2004). These other impairments will be addressed separately. The TMDLs described within this document were developed to address the water quality impairments associated with excess nutrient loadings.