Invasive dreissenid mussels, introduced to the Great Lakes in the 1980s, dominate the benthic community of Lake Michigan. Quagga mussels (dreissena rostriformis bugensis) are present in the lake with populations as dense as ~10,000 individuals/m2. These mussels have dramatically altered nutrient dynamics and food web structure within the Great Lakes. Dreissenids are sessile filter feeders that serve as integrators of local water quality conditions. Therefore, they can be useful as indicators of long-term change. Using a 14-year dataset from a 10-meter site near Sleeping Bear Dunes National Lakeshore in northeastern Lake Michigan, we examined trends in nearshore dreissenid density and condition. Although mussel density has remained relatively stable over time, we observed a significant decline in the mussel weight:length ratio, suggesting a decrease in mussel condition. The decline is particularly pronounced in small to midsize mussels. A potential driver of this trend is a change in the nutritional quality of phytoplankton in the study region, as revealed in measurements of seston nutrient stoichiometry. This may in turn have consequences for much of the Lake Michigan food web. We will discuss the implications for nearshore dreissenid populations and nutrient cycling in Lake Michigan.