The presence of Escherichia coli (E. coli) in surface waters is often attributed to fecal contamination from agricultural and urban/residential areas (human sewage and non-human wastes, such as wastes from birds and other wildlife). However, variation in E.coli concentrations from site to site and in contribution of agricultural vs. human sources are not readily understood. In addition, E.coli concentrations at a particular site may vary depending on the baseline level already in the river/lake water and sediments. The concentration of
E. coli in surface water depends for the most part on the runoff from various sources of contamination.
E. coli as an Indicator Organism
To help maintain water that is safe for swimming, routine monitoring for enteropathogens is necessary, but are difficult to detect. An indicator organism, such as E.coli, is used to determine fecal contamination. The presence of E.coli, a normally nonpathogenic intestinal organism of warm blooded animals, is easy to test for and is relatively more abundant than the enteropathogens thus leaving a safety margin for the detection of disease causing organisms.
Sacramento County Department of Health Service, Division of Public Health E. coli in the American River Frequently Asked Questions.
- Every lake, stream or river can have bacteria – including E. coli, which is found in the intestines
of mammals – from wildlife to humans
- Most E. coli strains are harmless and do not cause human illness
- The State’s Central Valley Water Board is conducting a yearlong study to help determine the
source of E. coli in the Lower American River
- Because bacteria can be in any public waterway, everyone should:
- Not drink recreational water or use the water for cooking
- Wash your hands or shower after swimming
- Not enter the water if you have cuts or open sores, as these are pathways for bacteria
to enter your body
- At this time, the levels of E.coli in other central valley lakes, streams and rivers are unknown
because the State’s Central Valley Water Board doesn’t have the same monitoring program
elsewhere that is employed for the Lower American River (hence the promotion of healthy
- The State’s Central Valley Water Board does not know the sources of the E. coli, and therefore
do not know if the strains in the Lower American River are dangerous and causes human illness
Escherichia coli (E. coli) are bacteria that live in the intestines of people and animals. Most E. coli are
harmless and actually are an important part of a healthy human intestinal tract.
There are hundreds of different strains of E.coli and only a few of them are causes of disease. Some E.
coli strains are pathogenic, meaning they can cause illness, either diarrhea or illness outside of the
intestinal tract. The types of E. coli that can cause diarrhea can be transmitted through contaminated
water or food, or through contact with animals or persons.
Shiga toxin-producing E. coli (STEC) make toxins that can cause severe illness. STEC is commonly heard
about in the news in association with foodborne outbreaks.
E.coli is a Title 17 reportable disease. Medical providers and labs are required by law to report cases to
local public health officials. To date, there have been no water-related E. coli illness cases from our
rivers and streams reported to Sacramento County Public Health.
Public health infectious disease investigators investigate every reported case of E. coli-related illness to
identify the source and stop the spread of the disease. Investigators notify those who may be at risk;
this typically includes close contacts. If public health officials decide there is a risk to the general public,
a public notification is sent out.
The Public Health Officer has local authority in determining if a recreational area needs to be closed. An
example would be if there was a known communicable disease outbreak or a known sewage release,
the Public Health Officer would be consulted to make this determination.
E. coli are generally found in all recreational waters. Because of this, additional testing must be
conducted by the Central Valley Regional Water Board to determine the source of E. coli (human,
mammal, and/or water fowl). This testing will only identify the source not the strain.
Things you can do to reduce the risk of STEC infection include:
- Do not eat undercooked meat. Cook ground beef to an internal temperature of at least 160 F.
- Check the temperature of the meat with a food thermometer.
- Do not drink unpasteurized (raw) milk, juice and cider.
Avoid drinking untreated water:
- Don’t drink or swallow water from rivers, streams, lakes, or pools.
- Untreated water should be boiled before use.
- All family members should wash their hands with warm, soapy water after using the toilet,
changing diapers, handling animals, and before preparing or handling food or drinks.
- Wash your hands and/or shower after swimming.
- Do not enter the water if you have cuts or open sores, as these are pathways for bacteria to
enter your body.
- Avoid algae blooms (brightly colored water) and trash in the water.
- Pay attention and follow any warning signs and postings. Do not access a water body if posted
warnings indicate it is not safe to do so.
- Contact your healthcare provider if you have concerns regarding your health after swimming in