DULUTH, Minn. (Northern News Now) – Visitors to the popular Park Point Beach may have noticed a sign over the weekend warning them to avoid the water due to high levels of bacteria.

The sign was put up by the Minnesota Department of Health (MDH), which conducts routine testing twice a week from Memorial Day through Labor Day weekend.

According to MDH, such warnings are very common along the shores of Lake Superior throughout the summer.

One of the tests last week in Park Point showed higher levels of E. coli bacteria.

“This E. coli indicator just tells us that there could be germs in the water that could make people sick,” said Trisha Robinson, chief of the MDH’s waterborne disease division. “But there is no additional testing being done to say, ‘Yes, that was actually the case’ or ‘No, that was actually not the case.'”

Robinson said follow-up testing the next day showed E. coli counts had dropped well below the limit. The alert was lifted early Monday morning after MDH received the results from the lab.

Euan Reavie, a Great Lakes water testing expert at the Natural Resources Research Institute, said E. coli numbers can be very localized and influenced by factors such as rainfall and temperature.

“The day after a big rainstorm, when the whole system has been flushed, it may actually appear cloudy, but a little cleaner. It doesn’t take long for all that nutrient mass to settle, and the bacteria take it up and start growing.”

However, Reavie said that unlike other harmful lake bacteria, the growth of E. coli can go unnoticed.

“E. coli is a trickier thing because you can’t see it with the naked eye like you can see algae,” Reavie said. “They’re in the water but they don’t really form a visible bloom, but it can still be a really bad situation to be swimming in, so that’s why they do the measurements and put up these warnings.”

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