A geographic information system (GIS) is being used to assist in the design and implementation of the U.S. Geological Survey National Water Quality Assessment Program (NAWQA) at the national-and the basin-study scale. Nation-wide data sets, such as hydrologic-unit boundaries, population density, crop types, physiographic provinces, and ecoregions, have been used to partition study units into homogeneous subareas for water-quality sampling. More spatially accurate versions of these data sets are being developed at the basin-study scale to evaluate the relation between water-quality data and available geographic data. In addition to geographic analysis, the GIS is useful for establishing a common database for individuals working on different aspects of the project. Spatial data can be displayed in a variety of ways, which enhances the flow of information and ideas between project personnel with different specialties.
1 U.S. Geological Survey, Box 25046, MS 415, Denver Federal Center, Lakewood, CO 80225