The report summarizes 20 years of data on Lake Michigan's chemistry, focusing on changes in water quality and sediment due to human and natural factors. Factors like temperature and mixing affect nutrient levels and pollutant dispersal in the lake. The study examines differences in chemical concentrations between different areas of the lake, like Green Bay and Grand Traverse Bay. It discusses various substances found in the water and sediment, including nutrients and contaminants, their sources, forms, and seasonal variations. The report also includes information on water quality standards and regulations for Lake Michigan.