Submersed aquatic vegetation (SAV) was sampled from 1994-2000 at fixed sires along established transects in Pool 13 of the Upper Mississippi River System (UMRS), as part of the Long Term Resource Monitoring Program (LTRMP). These data were used to quantify the annual percent frequency of occurrence and mean relative density of SAV within three backwaters (Brown\u27s Lake, Savanna Bay, and Spring Lake) and the impounded area of Pool 13. This investigation used Spearman rank correlation to assess the strength of bivariate relationships between measurements of SAV abundance and biological, physical, and hydrological variables at fixed water quality monitoring sites within vegetation monitoring areas. In backwater habitats, the percent frequency of occurrence and mean relative density of SAV exhibited significant negative correlations (P\u3c 0.05) with May-August median turbidity and mean velocity. Mean velocity and median turbidity were strongly correlated, which suggested that water inputs from channel habitats caused observed differences in water clarity, as well as subsequent differences in the percent frequency of occurrence and mean relative density of SAV. In the impounded area of Pool 13, the percent frequency of occurrence and mean relative density of SAV increased during the period of study and was strongly correlated with tooted floating leaved vegetation (RFV). None of the other physical or hydrological variables analyzed for the impounded area demonstrated significant correlations. The cause for the lack of significant relationships between independent variables and measurements of SAV abundance in the impounded area of Pool 13 are uncertain, bur the differences may be due to previously established SAV beds creating favorable near-shore habitat with increased water clarity and reduced velocities when compared to main channel habitat
