E. coli's the culprit in Olcott Beach closings
Aug. 12—For the fifth time this summer, swimming at Olcott Beach was temporarily banned on Tuesday due to an unsafe level of E. coli in the lake water. The ban was lifted by the county health department on Thursday, after follow-up water testing showed the bacteria counts had subsided.
Health department personnel test the water at "bathing" beaches in the county on a regular basis, from Memorial Day through Labor Day, to verify it's safe to swim. When bacteria counts are "unsatisfactory" a swim advisory is issued and remains in effect until the counts come down.
E. coli is a type of bacteria associated with fecal matter and it can cause gastrointestinal ailments such as stomach ache and diarrhea. It's naturally occurring in lakes, rivers, streams and ponds, according to Paul Dicky, director of the health department's environmental division.
The water at Olcott Beach and the mouth of Eighteen Mile Creek is tested at least once a week. Three samples are taken every Monday — 20 feet from the shore, 40 feet from the shore and at the mouth of the creek — and if E. coli levels are low enough then the beach stays open; if not, more samples are taken on Wednesday and, if needed, on Friday. The beach stays closed until the water tests "safe."
According to Dicky, the minimum threshold for keeping the beach open is 235 bacteria colony forming units per 100 milliliters of water. In the samples drawn this past Monday, the colony count was 20 at the mouth of the creek, 210 in the deeper lake water along the shore, and 370 in the shallow lake water, thus triggering the beach's closure.
"When you take a sample, it represents a snapshot in time," Dicky said. "You have to hope the picture of that sampling represents a broader window."
Luckily, Dicky said, none of the water testing done at Olcott Beach on a Friday turned up too-high E.coli counts, for that would have meant ordering the beach closed through the weekend.
To date this summer, the beach has been closed five times due to high E. coli. Dicky said it was closed seven times between May and early August 2021. There are fewer closures in recent years, he added. In 2011, Olcott Beach was closed 18 times due to high bacteria counts.
The health department has been trying to determine the source of the contamination, Dicky said. Ruminants found in the water samples indicate the fecal contamination is from grazing animals: cattle, sheep, goat, elk or deer.
"We were initially thinking that since this is showing up in Niagara County, then it might be cattle," Dicky said. "But the laboratory said that they weren't able to isolate which ruminant it was, (and) they said that they didn't think it was cattle."
Dicky believes that deer are the likely source, since they are the second most common grazers found in the county.
"We don't have a lot of goats, elk or llamas, but we do have a lot of deer," he said.
Elevated bacteria counts are sometimes associated with increased lake temperature (about 70 degrees), high winds from the north which stir sediment, or rain within 24 hours of water samples being taken.
