In 2013, the first of several Regional Stream Quality Assessments (RSQA) was done in the Midwest United States. The Midwest Stream Quality Assessment (MSQA) was a collaborative study by the U.S. Geological Survey (USGS) National Water Quality Assessment (NAWQA), the USGS Columbia Environmental Research Center, and the U.S. Environmental Protection Agency (USEPA) National Rivers and Streams Assessment (NRSA). One of the objectives of the RSQA, and thus the MSQA, is to characterize the relationships between water-quality stressors and stream ecology and to determine the relative effects of these stressors on aquatic biota within the streams (U.S. Geological Survey, 2012). To meet this objective, a framework of fundamental geospatial data was required to develop physical and anthropogenic characteristics of the study region, sampled sites and corresponding watersheds, and riparian zones. This dataset defines the geographic extent of the MSQA, and is one of the four fundamental geospatial data layers that were developed for the Midwest study.
The MSQA spans over 650,000 square kilometers, crossing 12 states: Illinois, Iowa, Indiana, Missouri, Ohio, Nebraska, Minnesota, Wisconsin, and small portions of Kentucky, Kansas, South Dakota, and Michigan. Originally, the geographic extent of the study was defined from the aggregate of selected Level III Ecoregions (U.S. Environmental Protection Agency, 2010; Omernik, 1987): Eastern Corn Belt Plains, Interior River Valleys and Hills, Western Corn Belt Plains, Southeastern Wisconsin Till Plains, Central Corn Belt Plains, and the northern subdivision of the Central Irregular Plains that spans southern Iowa and northern Missouri. Portions of the boundary were subsequently modified to include a few watersheds that crossed the original boundary, and generalized to eliminate detailed ecoregion borders. Despite these modifications, overall, the final MSQA boundary is representive of the extent of the original ecoregions selected for the study area.
The geographic information system (GIS) software and specific tools mentioned in this metadata document are from the ArcToolbox, version 9.3.1, a component of the ArcGIS for Desktop (Esri, 2012).
References cited in this document:
Esri, 2012, ArcGIS 9.3.1 for Desktop: Redlands, CA, Esri, accessed at http://www.esri.com/software/arcgis/arcgis-for-desktop.
Omernik, J. M., 1987, Ecoregions of the conterminous United States: Annals of the Association of American Geographers, v. 77, p. 118–125.
U.S. Environmental Protection Agency, 2010, NA_CEC_Eco_Level 3: Corvallis, Oreg., U.S. EPA Office of Research and Development (ORD) - National Health and Environmental Effects Research Laboratory (NHEERL), accessed January 2012, at ftp://ftp.epa.gov/wed/ecoregions/cec_na/NA_CEC_Eco_Level3.htm.
U.S. Geological Survey, 2012, The Midwest stream quality assessment: U.S. Geological Survey Fact Sheet 2012-3124, 2 p.
