Physical conditions differ among the Mississippi River and its major tributaries in Minnesota and Wisconsin. Analysis of the environmental framework of the basin and analysis of historical water-quality information by the National Water-Quality Assessment (NAWQA) Program shows that nutrients (nitrogen and phosphorus) in streams in the Upper Mississippi River Basin are influenced primarily by land use. In the Mississippi River, nutrient concentrations were greater downstream of the Minnesota

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... r and major wastewater discharge points in the Twin Cities Metropolitan Area (TCMA). Stream loads of nutrients (the amount of the constituent carried past a point on a stream during a given period of time) also increased downstream of the Minnesota River and major wastewater discharge points in the TCMA.