Lake Michigan’s habitats support a diverse array of plant and animal species and its waters continue to provide opportunities for swimming and recreational use. However, invasive species and other stressors continue to affect both water quality and the lake’s food web.
Lake Michigan continues to be a good source of high-quality drinking water and provides good opportunities for swimming and recreation. Most toxic chemicals continue to decline in the environment, however, restrictions on fish consumption continue to be advised in certain areas.
Overall, coastal wetlands are in Fair condition, due to a combination of wetlands with degraded plant and animal communities and healthy wetlands with some of the highest amphibian and bird species richness observed in the Great Lakes. In some nearshore areas, there is excessive growth of the nuisance algae Cladophora and toxic blooms of cyanobacteria occur in Green Bay. Aquatic habitat connectivity is considered Poor with over 80% of tributary habitat no longer accessible to migratory fish, however, projects implemented over the past decade to remove barriers or improve fish passage have increased connectivity, with more tributary habitat accessible for native fish like Lake Sturgeon.
Offshore, invasive filter-feeding mussels have contributed to overall lower phosphorus levels and less phytoplankton biomass. In the mid-2000s, zooplankton biomass rapidly declined and has since stabilized at reduced levels. This long-term decline of zooplankton, along with the decline in Diporeia, has contributed to a lower overall abundance of prey fish. Despite these challenges, increased natural reproduction of Lake Trout is evident, due in part to the successful control of invasive Sea Lamprey. Lake Trout is an important species that contributes to the multi-million dollar Lake Michigan sport fishery.
Groundwater quality is assessed as Good based on nitrate and chloride concentrations. Land-based stressors continue to impact the Lake Michigan basin. Shifts in long-term climate trends, such as increasing water temperatures and decreasing ice cover, are expected to have ecosystem implications.