Definitions: E. coli, Dissolved Oxygen.

E.coli (short for Escherichia coli), is a type of fecal coliform bacteria, and is commonly found in the intestines of animals and humans and is found in human and animal wastes. There are different kinds of E.coli bacteria some harmful to humans and some not. One strain of E.coli bacteria, E.coli O157:H7, can cause severe illness and death. E.coli O157:H7 has often been found in poorly cooked food but can be also be found in water and was the source of waterborne illness in New York, Washington and Walkerton, Ontario. Recent studies have shown that E.coli is a hardy pathogen and can survive for long periods of time especially in cold water.

The presence of E.coli in water is an indication of animal waste contamination or human sewage. The State of Michigan has a standard for how much E.coli can be in surface water; less than 300/100ml for swimming or full body contact.(130/100ml as a 30 day geometric mean, May1st-Oct.31), and 1000/100ml partial body contact (year around).

E.coli is also an indicator organism of contaminated or unsafe water. They are monitored in surface waters because their presence indicates fecal contamination is present. Because it is not feasible to test for all the disease-causing organisms that can be present in surface water, Michigan uses E.coli as an indicator because it is commonly found in animal and human wastes. If E.coli is present above certain levels, then other disease causing organisms may be present and a potential threat to human health.

Infection by E.coli O157:H7, can cause the following health effects: severe bloody diarrhea and abdominal cramps; sometimes the infection causes non-bloody diarrhea. Often no fever is present. Symptoms usually appear in 2-4 days but can take up to 8 days. Most people recover without specific treatment in 5-10 days. Children under the age of five, the elderly and people whose health is weakened (long term illnesses such as cancer or AIDS) are at greatest risk for severe illness. In some people there is a complication called hemolytic uremic syndrome, in which the red blood cells are destroyed and the kidneys fail. About 2-7% of infections lead to this complication. In the United States hemolytic uremic syndrome is the principle cause of acute kidney failure in children, and most cases of hemolytic uremic syndrome is caused by E.coli O157:H7. With intensive care the death rate for hemolytic uremic syndrome is 3-5%.

E.coli can cause severe illness if ingested and is also an indicator of other disease causing organisms in water.

DO (Dissolved Oxygen)-- Almost all plants and animals require oxygen to breathe and live.  This is true for aquatic species as well, and oxygen is present in water in a dissolved form.  Most aquatic species have gills or special tissues as breathing mechanisms. Because cold water absorbs more oxygen, DO is usually higher in winter and lower in summer. Excess nutrients (manure, fertilizer) in water feed the growth of algae.  Bacteria in water consume and decompose this organic matter, and bacterial decomposition consumes a great deal of dissolved oxygen.  Low DO is an indicator of organic pollution.  Michigan has a water standard for DO -- 7mg/L or higher for coldwater stream, 5mg/L or higher for warmwater streams. Less than 3mg/L kills fish.