The U.S. Geological Survey (USGS), in cooperation with the U.S. Fish and Wildlife Service (USFWS) and the U.S. Environmental Protection Agency (EPA), identified the occurrence of contaminants of emerging concern (CECs) in water and bottom sediments collected in 2013 at 57 sites throughout the Great Lakes Basin. The 2013 effort is part of a long-term study that began in 2010. Included in this directory are collection methods, references to or descriptions of analytical methods used, data for samples collected in 2013, and associated quality-assurance data. Samples were collected from April through October 2013 by USGS, USFWS, and/or EPA personnel. Study sites include tributaries to the Great Lakes located near Duluth, Minnesota; Kewaunee, Wisconsin; Appleton, Wisconsin; Detroit, Michigan; Grand Rapids, Michigan; St Clair, Michigan; Cleveland, Ohio; Wanakena, New York; and Potsdam, New York (see "2013 Site List"). During this study, 93 environmental samples and 6 field replicate sample pairs of surface water, 3 field blank water samples, and 3 laboratory-matrix spike water samples were collected or prepared. Additionally, 49 environmental samples, 4 field replicate sample pairs, and two laboratory-matrix spike samples of bottom sediment were collected or prepared. Water and bottom-sediment samples were analyzed at the USGS National Water Quality Laboratory in Denver, Colorado, for a broad suite of CECs.