Madison Lake is one of at least about 27 Ohio public beaches which have swimming advisories in effect because of excessive bacteria.
The Ohio Department of Health issued a contamination advisory last week.
According to the ODH website, a recent test revealed the lake had 500 colonies of E. Coli per 100 milliliters of water. To be considered safe, Ohio Water Quality recommends public beaches not exceed 235 colonies.
The 106-acre lake was under a similar advisory for 14 days last July, as well as for 54 days during three different advisory periods in 2012.
The Ohio Department of Natural Resources monitors the lake. It is tested every week starting with the onset of swim season in May.
The state health department posts swim advisories when E. Coli bacteria in water samples is high enough to make people sick. Children, the elderly, and people with weakened immune systems are particularly advised against swimming in those conditions.
If ingested, the bacteria may lead to severe diarrhea, abdominal pain and vomiting, according to the U.S. Food and Drug Administration.
The ODH website states the source for the pollution is “unknown.”
Heavy rain has contributed to the higher readings, washing run-off sewage, fertilizer and farming chemicals from land surfaces into lakes and rivers, according to published reports.