Which lake was referred to as the "dead" Great Lake?

Lake Erie is often referred to as the "dead" Great Lake due to its historical struggles with pollution and environmental degradation. This designation arises from the lake's shallow depth and the significant impact of human activities within its watershed, leading to issues like eutrophication. Eutrophication occurs when excess nutrients, primarily from agricultural runoff and wastewater, enrich the water, promoting harmful algal blooms that deplete oxygen levels. The lack of oxygen can create dead zones where aquatic life cannot survive, hence contributing to the lake's "dead" moniker.

Over the years, various environmental policies and conservation efforts have been implemented to improve water quality in Lake Erie, demonstrating the capacity for recovery. However, its past struggles have solidified its reputation as the most biologically impaired of the Great Lakes, further reinforcing its association with the term "dead." This status is significantly distinct from the other Great Lakes, which have different ecological challenges but have not earned the same designation.