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A Primer for Safe Swimming

So you want to go for a swim in the Mad River this summer?  If you don’t want to become ill there are a few things you may want to know…

Who’s Watching the Water?

For the past 20 years citizens in the Mad River Valley have been monitoring the water quality of the Mad River and the many brooks and tributaries that flow into it.  The project, known as “Mad River Watch”, is one of the oldest of its kind in the country and has been a role model for many other community groups.  Mad River Watch was started as a project of the “River Watch Network” whose co-founder, Jack Byrne, resides in Moretown.  As the first Executive Director of the River Watch Network, Jack extended the work of citizens in Vermont’s Ottaquechee River who had been using monitoring information to galvanize community support to successfully clean up the grossly polluted Ottaquechee River.  Using this model of citizen based monitoring to enact beneficial environmental change; Jack worked to set up organizations from the Mad River to the watersheds of the Hudson, the Mississippi, the Rio Grande, and even the Danube.

Mad River Watch was adopted by the then newly formed Friends of the Mad River (FMR) in 1994, where Jack resides as Vice President.  Every other week during the summer swimming months, volunteers make their way around the Mad River Watershed collecting samples from 37 strategically selected sites which range from the most popular swim holes to obscure tributaries where current land use may be affecting water quality.  At the site, volunteers collect observations onto a field sheet and measure physical and chemical properties of the water such as its temperature and pH.  A water sample is then taken and, collectively, brought to the Friends of the Mad River office at the General Wait House.  A lab is set up at the office and each sample is processed to determine the level of E. coli colonies present at the time of collection.

Frequently Asked Questions

What is E. coli?

E. coli is short for Escherichia coli. E. coli is the head of the large bacterial family, Enterobacteriaceae, the enteric bacteria. E. coli is a type of fecal coliform bacteria commonly found in the intestines of humans and other warm-blooded animals. They have the ability to grow at elevated temperatures.

How is E. coli beneficial to humans?

Beneficial E. coli, which greatly outnumber pathogenic E. coli, break down vitamins from undigested food in our large intestine. This, in turn allows us to assimilate the vitamins into our bloodstream.  Without these beneficial E. coli, humans would not effectively absorb vitamins such as vitamin K from our food.  The first common misconception to break is that all E. coli are bad and cause sickness.

What kinds of pathogenic E. coli are there?

Pathogenic E. coli is responsible for three types of infections in humans: urinary tract infections (UTI), neonatal meningitis, and intestinal diseases (gastroenteritis). Uropathogenic E. coli are the cause of 90% of the urinary tract infections (UTI) in humans. The bacteria enters the body via the urethra and attaches itself to the urinary tract.  Neonatal meningitis is an infection which affects the meninges (coverings of the brain) of 1/2,000 - 4,000 infants. This bacterium enters the bloodstream of infants from the nasopharynx or intestinal tract. Pathogenic E. coli is best known for its ability to cause intestinal diseases. There are five classes (virotypes) of E. coli that have been identified to cause diarrheal diseases.  For more info visit Bacteriology at University of Wisconsin-Madison Home Page. The University has a great site on Pathogenic E. coli. The address is

How do E. coli and other fecal coliforms get in the water?

E. coli comes from human and animal (wildlife, livestock, and pet) wastes. During rainfalls, snow melts, or other types of precipitation, E. coli may be washed into creeks, rivers, streams, lakes, or groundwater.  E. coli contamination may also occur on a steady basis if a failed septic system, or improperly located outhouse, is leaching sewage into the water.

How is testing for E. coli in water useful?

The presence of E. coli in water is a strong indication of recent human or animal waste contamination.  Sewage in water risks the presence of intestinal parasites, pathogenic E. coli, or other disease causing organisms and viruses that may pose a health risk to humans.  Water quality testing on a regular basis at strategic locations can help to identify and eventually eliminate contamination sources as well as to develop an understanding of the conditions that might lead to elevated contamination levels so that bathers can make informed decisions about the health risk of swimming.  

How much E. coli is too much?

Swimming in the great outdoors and enjoying the wide variety of wildlife we share with it is one of the many reasons to love Vermont summertime.  Naturally, some “waste” from wildlife makes it into local water.  In fact, recent local studies tell us that under moderate rainfall, E. coli levels will be found in waters running off of completely undisturbed, forested watersheds at levels in excess of Vermont’s State standard.  In light of these newly emerging scientific findings, Vermont State scientists are beginning to re-evaluate Vermont’s Class B water quality standard which sets the maximum tolerable E. coli level at  77 colonies per 100 ml of sampled water (the most stringent standard in the nation).  This standard has been the benchmark for Mad River Watch, and constitutes a risk that for every 1000 Mad River swimmers, we are 75% sure that 3.4 persons will become ill.  To be 95% sure of this illness rate, the E. coli count would have to increase to 187 E. coli/100ml.

What are the limitations of testing for E. coli?

The Mad River Watch program reports E. coli levels based on a single sample collection that is taken every other Saturday morning, however, studies have shown that E. coli levels can vary of short distances and times.  Therefore, actual E. coli levels at the time you choose to have contact with the Mad River or one of its tributaries may vary significantly from the E. coli test results that are posted in the newspaper and at  Additionally, without DNA testing of fecal matter, identifying the source of a collected contamination will remain the work of scientists, neighbors, and landowners who are ultimately responsible for making informed decisions that minimize the impact of septic, livestock, and pet waste on local surface and ground water.

How can I use the Mad River Watch data to make an informed decision?

Using river data from the U.S. Geologic Survey’s gauging station in Moretown ( FMR is examining the relationship between the volume of water flowing in the river prior to and during the dates that we have collected E. coli samples over the past nine years.  We have summarized the river’s flow into the following six categories that local swimmers should be able to recognize based on casual observations of the weather and water levels.
•    LS= low and steady:  It has not rained in several days and the water is low.
•    LR= low and rising:  A recent rainfall has caused the low flowing river to rise.
•    LD= low and declining:  Rain brought a low river up earlier in the week, but the flow is dropping
•    HS= high and steady:  The river has been running higher than normal for several days.
•    HR= high and rising:  Recent rains have caused a high river to rise even more.
•    HD=high and declining:  After reaching a peak flow, dry weather has returned and the flow is falling.

Our data indicates that on the main stem of the Mad River E. coli levels exceed the state standard 73% of the time that we sampled when the river had been low for several days and rose quickly at the time of our sampling (such as was the case this past weekend 6/14/03).  We think that this can be attributed to a sudden flush of contamination into the streams due to a rain event that has caused the water levels to rise.  Other times of concern, in general, seem to be when the levels are “high and steady” and “high and rising”.  We hope that swimmers will learn to become familiar with these changing conditions and the level of risk that is associated with them and begin to make informed decisions based on observation rather than Mad River Watch’s “posted” E. coli recording

What other precautions could I take?

•    If you have a private well, get the water tested regularly
•    Avoid swallowing river water while swimming.
•    Anyone with a diarrhea illness should avoid swimming in public pools or lakes, sharing baths with others, and preparing food for others.
•    Children under the age of five, the elderly, and people who have compromised immune systems i.e. (cancer or AIDS) are at greater risk of illness due to contaminated water.  

For more info visit

What could I do to help prevent water pollution in my community?

•    Make sure to have routine septic system maintenance.
•    When using lands recreationally practice proper sanitary outdoorsmanship (Make sure to “go” at least 200 feet from a water source)
•    Your pet should follow in the same footsteps and if not, you should pick up after them.
•    Report any dumping of household or municipal wastes, i.e.(baby diapers, sewage).
•    Support ecologically sustainable farming and wastewater treatment practices.
•    Support ecologically sustainable community development practices.

Who do I contact for more information about Mad River Watch?

Friends of the Mad River,, 496-9127.

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