Lisa S. Alter
Bacteria, viruses, and other microorganisms that can cause disease are called pathogens. The primary sources of these are older sewer systems that have combined stormwater and sanitary systems that overflow during storms. Other sources include; sewage treatment plant malfunctions, illegal connections to storm sewers, vessel sewage discharges, failed septic systems, stormwater runoff, and animal wastes. (Beristain, 1990)
Checking for these pathogens is done indirectly. Coliform bacteria, found in the digestive tracts of all warm-blooded animals are analyzed. Coliform bacteria are not harmful to humans but because they are always present in sewage and animal waste, they indicate the possible presence of pathogens. When high coliform counts are found, shellfishing is banned and beaches are closed to swimming. Diseases most often due to pathogen exposure, in this part of the world include; gastroenteritis, salmonellosis, and hepatitis. (Atkin, Bangser, Jacobson, Smith, Wade, Backer, 1991)
The estimated percentage of fecal coliform discharged yearly into the Sound comes from the following sources; 51.6% from rivers (from upstream sewer treatment plants) and nonpoint sources (ex. failing septic systems), 47.3% from urban runoff, which includes combined sewer overflows, and 1.1% from sewage treatment plants and industrial sources discharging directly into the Sound. (Beristain, 1990)