Section 303(d) of the federal Clean Water Act (CWA) and the U.S. Environmental Protection Agency's (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. This list of impaired waters is commonly referred to as the 303(d) list. For each WQLS, the State is to either establish a Total Maximum Daily Load (TMDL) for the specified substance that the waterbody can receive without violating water quality standards, or demonstrate that water quality standards are being met. Zekiah Swamp (basin code 02-14-01-08) was identified on the States 1996 303(d) list as impaired by nutrients (1996 listing), suspended sediments (1996 listing), copper (Cu) (1996 listing), lead (Pb) (1996 listing), selenium (Se) (1996 listing), zinc (Zn) (1996 listing) and impacts to biological communities (2002/2004 listing). All impairments were listed for the tidal waters except for the impacts to biological communities and nutrients, which were listed for the non-tidal waters. The listings for Cu, Pb, Se, and Zn were based on a water quality assessment found in the 1996 305(b) report developed by the Maryland Department of Natural Resources (DNR). The Water Quality Analyses (WQAs) of Cu, Pb, Se, and Zn for the Zekiah Swamp was conducted by MDE using recent water column chemistry data and sediment toxicity data to determine if an impairment currently exists.