When will swimming ban end at Presque Isle's Beach 6? Official: 'Probably days, not weeks'

A Presque Isle State Park lifeguard stood Tuesday afternoon at the entrance of the Beach 6 parking lot.

Instead of sitting in a raised white chair and watching swimmers, the lifeguard's job that day — and for the next several days at least — was to notify visitors that no swimming was permitted at the popular beach.

Swimming restrictions due to high levels of E. coli bacteria usually occur several times a year at various Presque Isle beaches but this particular restriction is different, and could last longer than a typical one.

"Most of our swimming advisories and restrictions are based on a daily water sampling," said Matthew Greene, Presque Isle's operations manager. "This one is based on a 30-day geometric mean of results."

Swimming is restricted at a Presque Isle beach if its average of three water samples taken on a particular day is more than a most probable number of 999 particles of E. coli per 100 milliliters of water. Most probable numbers replace colony-forming units that were associated with previous E. Coli tests, according to the Erie County Department of Health.

Swimming in water that contains high amounts of E. coli can cause skin infections and gastrointestinal illness, especially in children and people with weakened immune systems. E. coli is also a marker for other bacteria.

But swimming is also restricted if a beach's geometric mean, a mathematical formula based on daily E. coli testing results from the previous 30 days, is more than a most probable number of 126.

Restrictions due to high geometric means are much more rare at Presque Isle than ones due to high daily averages. The last one occurred in 2018 at Beach 11.

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That restriction was issued Aug. 6, 2018 and remained in place at Beach 11 for the rest of the summer. Greene said he doesn't expect Beach 6's swimming restriction to last nearly as long.

"We don't have any major indicators that show a long-term restriction at Beach 6," Greene said. "It will probably be days, not weeks."

Any extended swimming restriction at Beach 6 is a concern, since it is one of Presque Isle's most popular beaches. Although Beach 6 remains open for nonswimming activities, including sunbathing and volleyball, Greene said visitors are going to other beaches where they can enter the water.

"Most of them are going to Beach 8 and that is taxing operations there," Greene said. "We are having one of our busier days of the summer there (on Tuesday) and it's a weekday."

The length of Beach 6's swimming restriction became even more important Wednesday afternoon, when swimming was restricted at three more Presque Isle beaches — 8, 9 and Barracks Beach — due to their water samples exceeding the 30-day geometic mean.

One of the highest E. coli counts since 2015

Beach 6's swimming first daily swimming restriction in 2023 was posted the day after June 27 sampling showed 1,900 CFUs of E. coli, one of the highest daily averages of any Presque Isle beach samples taken since 2015.

Several other daily averages taken at Beach 6 in late June and early July has a most probable number between 500 and 600. As a result, its geometric mean on Tuesday exceeded the 126 limit for swimming.

"The results from June 27 were so high, and other numbers are high enough, that it will take quite a few low results to bring down the geometric mean," said Breanna Adams, director of environmental health services for the Erie County Department of Health. "It's a matter of math."

In an effort to reduce the geometric mean, sampling is being done every day at Beach 6. But if the new samples aren't low enough, the swimming restriction could remain in place until the June 27 results are outside the 30-day window.

What caused Beach 6's high E. coli counts?

The cause of Beach 6's high E. coli results aren't known for sure but Greene has a theory.

While Beach 11's swimming restriction in 2018 was due to a high amount of goose feces at the beach, Greene said birds are not the reason for Beach 6's restriction.

"It's apples and oranges," Greene said. "We did have beach nourishment recently at Beach 6, so the sand there wasn't as well packed as it usually is. The winds pushed more of it into the water and that likely increased the (E. coli) levels."

Studies have shown that sand acts as a reservoir for E. coli and other bacteria.

Whether Beach 6's swimming restriction continues for just a couple more days or longer, Greene said he's confident people will be swimming again soon at the popular beach.

"Beach 6 sits in a geographic part of the peninsula where the currents are strong and there is heavy erosion," Greene said before Wednesday's additional restrictions were announced. "Lots of water passes by that beach and it will clear things up."

Contact David Bruce at [email protected]. Follow him on Twitter @ETNBruce.

This article originally appeared on Erie Times-News: Presque Isle State Park's Beach 6 has longer-term E. coli swimming ban