Sewer outflows are a major cause of bacterial pollution

Disease-causing microorganisms, including bacteria, viruses, and other single-celled organisms, are referred to as pathogens. While the vast majority of bacteria are harmless or beneficial, some, like Salmonella, cause human health problems. Commonly used bacterial indicators of water pollution like Escherichia coli and Enterobacter, normally associated with fecal waste, are used to assess pathogen levels in waters introduced through sanitary sewer overflows, faulty septic systems, or poorly managed livestock operations. (From Mobile Bay National Estuary Program's CCMP)

Common Sources: Pet Waste, Sewer Overflow, Improperly managed Livestock

Things you can do: Pick up After Your Pet, Maintain Septic System