Master's Thesis from the year 1998 in the subject Environmental Sciences, The University of Texas School of Public Health, language: English, abstract: This project investigates the transport of sediment and associated contaminants through the lowerportion of the Rio Grande/ Rio Bravo International Watershed. A preliminary review of water quality, bed sediment, and reservoir sediment-coring data in the watershed reveals a complex hydrological system, with varying potential sources of contamination. Within the lower portion of the watershed (defined as from the dams at Elephant Butte Reservoir in New Mexico and Red Bluff Reservoir in Texas co the Gulf of Mexico) arsenic, lead, and mercury appear at levels and/ or trends which may be of concern. Through the use of a geographic information system, this project evaluates the extent of contamination from selected toxic substances, identifies potential sources and/ or naturally-occurring conditions for the contribution of these toxic substances, and evaluates the potential for using Geographic Information Systems to model the watershed. The project uses data collected over the thirty year period from 1966 - 1996 by the Texas Natural Resource Conservation Commission, the United States Geological Survey, the International Boundary and Water Commission, and the United States Environmental Protection Agency. The project utilizes water quality, bed sediment, sediment coring, land use, land cover, soils, water-quality permitting, precipitation, flow, and reservoir-release information to attempt to derive a model depicting the movement of sediment through the watershed. Because the United States federal government has not promulgated standards for sediment (as of 1998), the project references standards from both the State of Washington and Canada for screening of sediment quality.