Loon Lake near Antioch in northern Illinois is a glacial lake system made up of East Loon, West Loon, and separate North Loon rather than a single lake. It is an important habitat for fish, birds, reptiles, and amphibians, including the endangered blacknose shiner. West Loon is deeper and clearer, while East Loon is slightly larger, shallower, and less transparent, giving West Loon a more recreational character and East Loon more of a nature focus. The lakes also reflect a long history of human use, including ice harvesting, while facing modern ecological pressures from invasive zebra mussels, runoff, and development-related pollution.