Data collected between 1993-1995 shows that over 55% of Mobile Bay had bottom dissolved oxygen levels below 4 mg/l, and 30% showed levels below 2 mg/l, both representing substandard conditions.

In addition, portions of the following rivers do not fully support their current or proposed water use classifications because of nutrient enrichment and/or low dissolved oxygen: Fowl River, Dog River, Lower Mobile River, Chickasaw Creek, Three Mile Creek, and Tensaw River.

A substantial volume of data exists on the levels of toxics and contaminated sediments in Mobile Bay. The EPA has classified Mobile Bay as an Area of Probable Concern with regard to sediment contamination, classifying sediments in some areas of Mobile Bay as poor and acknowledging a great deal of concern about accumulated toxics.