Quantitative assessment of mixing of suspended sediment downstream of large river confluences poses enormous challenges because of the large scales involved. This paper presents a new approach to quantifying spatial patterns of mixing at and downstream of large river confluences based on satellite remote sensing. SSCs are modeled by calibrating a predictive model using spectral information from Landsat remote sensing with data on sediment loads collected at U.S. Geological Survey gaging stations. The model is used to predict the spatial distribution of SSCs over a 110 km reach of Mississippi River downstream from the confluence with the Missouri River. Mixing across and along the river is calculated at 500 m intervals based on spatial averaging of information with the intervals. An example of the results of the model are presented to illustrate its value in determining the factors that influence mixing downstream of confluences.