This report presents the data collected for a study of the dissolvedmineral load contributed by surficial sources to Great Salt Lake, Utah. The study was conducted by the U.S. Geological Survey in cooperation with the University of Utah durinq the period from July 1959 through June 1962, and is part of an overall investigation of the Great Salt Lake basin by the University. Financial support for the study was provided by the U.S. Geological Survey and by the University of Utah Research Fund and Uniform School Fund. Some of the data presented in this report were obtained as part of cooperative programs between the Geological Survey and other agencies. The study was conducted under the immediate supervision of J. G. Connor (to July 1961) and R. H. Langford (from AuguGt 1961), district chemists in charge of water-quality investigations in Utah by the U.S. Geological Survey. A. J. Eardley, Dean, College of Mines and Mineral Industries, Univcraity of Utnh, represented the University in Lhe cooperative study and in review of the findings. Personnel of other Geological Survey offices in Salt Lake City and Logan, Utah, aided in the collection of samples and provided waler-c.lischctrge data. The sampling program in the lower Bear River was carried out by personnel of the Bureau of Sport Fisheries and Wildlife, U.S. Department of the Interior. Local observers sampled the lower Jordan River and the Weber River at Gateway. The basic data were obtained to define the chemical composition of streams, drains, and springs discharging into the Great Salt Lake area and to define the chemical composition of the lake brine itself. Most of the data included in this report were obtained during a period when inflow to the lake was low and when the water surface of Great Salt Lake was at or near its lowest recorded level. The basic data are grouped in seven tables; each table includes data for several sources within the unit represented by the table. Mean daily discharges are given for sampling sites located at or near gaging stations, and measurements of instantaneous discharge or estimates of discharge are given for other sampling sites. For analyses of samples of lake brine 5 collected south of the railroad fill, the stage of Great Salt Lake is reported to the nearest O. 05 foot based on records collected at the Salt Lake Co. Boat Harbor. Lake stage is not reported for analyses of samples collected north of the railroad fill because of suspected differences in water-surface elevation between the two parts of the lake. The location of each sampling site is reported to the nearest section and is keyed by number to the map on Plate 1. The criteria used in collecting the samples included: 1) selection of sampling sites to insure adequate mixing of upstream tributary waters at the sampling section, 2) selection of the most representative sampling pointwithregard to the stream cross section, and 3} scheduling the sampling frequency to ascertain accurately the yearly average concentration. Each sample was analyzed according to methods commonly used by the GP.ologicn l Survey (Rainwater and Thatcher, 1960). Iodide was determined by a modification of the method of Rossum and Villarrus (196 0). Density was determined if the specific conductance exceeded 10,000 micromhos. Great Salt Lake brine samples were diluted with distilled water prior to analysis.