Some types of bacteria are naturally found in streams and waterbodies. At low levels bacteria are essential to the health of a waterbody. As bacteria levels increase, the likelihood of an outside contamination source increases. For example, fecal coliform bacteria, a bacteria present in human and animal intestines, is rare in unpolluted water. High levels of fecal coliform bacteria indicate sewage (a source of fecal coliform) entering the waterbody.
In addition, disease causing pathogens flourish in growing conditions similar to fecal coliform bacteria. Therefore a high level of fecal coliform in stream water indicates that more serious pathogens, possibly from the same source, could be contaminating the water.
Possible bacteria pollution sources:
- Animal and pet waste
- Septic system failure
- Poor pasture management
- Urban runoff
- Sewage from stormwater overflows