Cattle standing in Pomme de Terre River

There are countless numbers of bacteria, viruses, and other microorganisms in the environment. Most are beneficial, serving as food for larger organisms, and playing critical roles in organic matter decomposition, fixation of nitrogen, and digestion of food. Only about 10 percent — known as pathogens — are harmful and, if ingested by humans, cause illness or even death. Symptoms of waterborne diseases may include gastrointestinal illnesses such as severe diarrhea, nausea, and possibly jaundice as well as headaches and fatigue. However, these symptoms are not associated only with disease-causing organisms in drinking water.

E. coli (Escherichia coli)

In water quality monitoring, specific disease-producing (pathogenic) organisms are not easily identified. Testing for them is difficult, expensive, and time-consuming. Instead,  Minnesota uses a bacteria called E. coli as a water quality standard, which can indicate the presence of pathogens. Protozoa and microorganisms such as giardia and cryptosporidia also cause disease; their presence may be indicated by E. coli.

Bacteria sources

The behavior of E. coli in the environment is complex. Seasonal weather, stream flow, water temperature, and proximity to pollution sources can all affect the amount of bacteria found in water. In addition, bacteria in stream sediments can survive for extended periods and may reproduce. E. coli found in Minnesota rivers and streams may come from human, pet, livestock, and wildlife waste and is more common in heavily populated or farmed areas. Bacteria may reach surface water through malfunctioning or illicit septic system connections, urban stormwater, manure spills or runoff, and more. Along with improved wastewater and stormwater management, properly managing manure storage and land-applied manure can help reduce bacteria contamination in lakes, rivers, and groundwater.