Pathogens’ presence indicates that water is contaminated by human or animal waste. Persons who come into contact with pathogens found in water can suffer headaches, diarrhea, cramps, nausea or other gastrointestinal illness. Two common pathogens found in water are Giardia and Cryptosporidium. These parasites are the cause of two of the most common waterborne diseases in the U.S. Both can persist in the environment for months and are highly resistant to disinfection. Young children and people with compromised immune systems may be particularly at risk from pathogens. Certain species of fish and wildlife are unaffected by these microbes while other species experience symptoms similar to humans.
Pathogens can enter waterways by way of sewer overflows, leaking sewer lines, and polluted stormwater that washes bacteria from undisposed pet waste into the nearest stream. Pet waste that is left in the street, dog park, or even a person’s backyard contributes to major water quality problems in Nashville. In agricultural areas, poorly chosen feeding, watering, and waste management locations can allow pathogens to make their way into our water. In rural settings, failing septic systems are often significant contributors to pathogen impairments.
In urban areas, high concentrations of pathogens are most often associated with heavy rainfall, which causes sewer system problems and carries pathogens from animal waste into our waterways.