Geographic Information Systems

Case Study

Report on Nine Aggregate Ecoregions

The strategic plan of the U.S. EPA calls for a survey and report on the condition of the Nation’s lakes, rivers and streams. GLEC is the lead contractor for this important multi-year effort. In support of this project, EPA asked GLEC to construct nine unique ecoregions for the conterminous U.S. and then analyze and report on each ecoregion’s physiographic, ecological, and anthropogenic characteristics. GLEC’s GIS specialists combined and modified existing detailed ecoregions into the nine new ecoregions, and then overlaid pertinent spatial data such as hydrography, climate, habitat, land cover, census data, pollution, and industrial and agricultural activity. Spatial analysis techniques were then employed to extract statistics and characteristics of each ecoregion.

Figure 25. Ecoregions surveyed for the WSA (U.S. EPA/WSA).
Click image to enlarge.

The ecoregion map provides a logical backdrop for the probability-based water quality survey data generated from the field sampling efforts. The project required extensive literature research in order to relate narrative profiles that describe the natural features, natural history, ecology, and human impacts within each ecoregion. The nine aggregate ecoregion map has been published in EPA’s Wadeable Streams Assessment report and will be included in a comprehensive report to the U.S. Congress on the health of the nation’s waters.

In addition to the GIS components of the survey of the nation’s waters, GLEC is responsible for study design, logistics support, field crew training and field sampling support for assessing habitats, chemistry, and macroinvertebrate health.