Physical and aquatic biological conditions differ among the Mississippi River and its major tributaries (the St. Croix and Minnesota Rivers) in Minnesota and Wisconsin. The quality of surface water and the ecological condition of rivers affect the ways in which we use them. The St. Croix River is used for recreation; the Mississippi River is used for recreation and is a corridor for commerce; and the Minnesota River primarily drains agricultural lands. Analysis of the environmental framework of the basins and water-quality and ecological information by the National Water-Quality Assessment (NAWQA) Program shows that the conditions of the rivers are a product of a combination of factors including climate, hydrology, geology, soils, land use, land cover, water management, and water use.
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USGS Numbered Series
Causes of Variations in Water Quality and Aquatic Ecology in Rivers of the Upper Mississippi River Basin, Minnesota and Wisconsin