The Upper Mississippi water resource region is one of 21 major geographic areas, or regions, in the first level of classification used by the United States Geological Survey to divide and sub-divide the United States into successively smaller hydrologic units. These geographic areas contain either the drainage area of a major river, or the combined drainage areas of a series of rivers.[1][2]
The Upper Mississippi region, which is listed with a 2-digit hydrologic unit code (HUC) of 07, has an approximate size of 189,968 square miles (492,010 square kilometers), and consists of 14 subregions, which are listed with the 4-digit HUCs 0701 through 0711. In a 1975 report, the region was described as "rich in water - surface water is plentiful, and ground water is a large, important, and manageable resource."[3]
The Mississippi River Basin below the confluence with the St. Croix River Basin to and including the Root River Basin west of the Mississippi River and the La Crosse River Basin east of the Mississippi River, excluding the Chippewa River Basin.
The Mississippi River Basin below the Root River Basin west of the Mississippi River and the La Crosse River Basin east of the Mississippi River to Lock and Dam 13, excluding the Wisconsin River Basin.
Located in Illinois, Iowa, Minnesota, and Wisconsin.
The Mississippi River Basin below the confluence with the Des Moines River Basin to the confluence with the Missouri River Basin, excluding the Illinois River Basin.
