Fecal Bacteria

What is Fecal Bacteria?

Fecal bacteria are bacteria from animal (including human) waste or feces, and are measured as a concentration of bacterial colonies (colonies/100mL) present in the water. Fecal bacteria are a diverse group of microorganisms, and there are several different groups of fecal bacteria that are used for monitoring water. For this study, we measure the concentration of Enterococcus fecal bacteria, which are used as an indicator for potential sewage contamination and human health risk from water contact. Fecal bacteria enter waterways through stormwater runoff that carries fecal bacteria from animal waste deposited throughout the environment, such as pet waste, and through overflows of human sewage from septic tanks, sanitary sewer pipes, and wastewater treatment plants.

More information

Why is Fecal Bacteria important?

Enteroccocus fecal bacteria are a reliable indicator for waterborne pathogens that are excreted by mammals and humans, such as Staphylococcus, Hepatitis A, Cryptosporidium, West Nile Virus, and other microorganisms that can cause gastrointestinal illness and skin and eye infections. For this reason, collection of this data is important for assessing the human health risk of recreational water contact.

How do we measure Fecal Bacteria?

Fecal bacteria are measured through the collection of a water sample for analysis by a laboratory. We collect a water sample from halfway between the water’s surface and river bottom at each station, store samples on ice, and deliver samples the same day to the laboratory for analysis. We assess the Enterococcus fecal bacteria data using the State of Maryland’s numeric human health thresholds for body-contact water recreation (“Low Risk” < 61 colonies/100mL; “Medium Risk” 61 - 151 colonies/100mL; “High Risk” > 151 colonies/100mL).