Watershed Relations and Changes

(UMRB) is a major sub-basin of the entire Mississippi River, one of the largest and most diverse ecosystems in North America. The length of the Upper Mississippi River (UMR) is approximately 800 miles (1,287 km). The drainage area of the basin is approximately 189,189 square miles (489,980 km2) and contains about 15 percent of the drainage area of the entire Mississippi River Basin. The Basin includes portions of Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, South Dakota, and Wisconsin (Figure 5-1). More than 30 million people live in the basin that drains extensive metropolitan areas, forests, and farm lands. Major cities include Minneapolis and St. Paul, Minnesota; the Quad Cities (Bettendorf and Davenport, Iowa, and Moline and Rock Island, Illinois); St. Louis, Missouri; and Peoria and Chicago, Illinois, on the Illinois Waterway. The UMRB has 12 major tributaries (see Table 7-1) whose influence on water quality are discussed in Chapter 7. Figure 5-2 (following page) illustrates the major and minor tributaries of the UMRB. The total length of basin streams mapped by the U.S. Geological Survey at 1:100,000 scale is about 30,700 miles (49,406 km). In Illinois, the state mapped streams at 1:24,000 scale maps and identified over 25,000 miles of Mississippi River tributaries in Illinois alone.