Ontario Beach Park closed for swimming due to high E. coli levels and clarity issues

FRIDAY UPDATE: Results from Thursday water testing posted on the state website indicate E. coli levels are back to within acceptable limits. However, clarity issues remain and the beach is closed Friday. Heading into the holiday weekend, the county suggests calling 585-753-5887 before making plans to swim.

CHARLOTTE, N.Y. (WROC) – If you took a trip to Ontario Beach Park to cool off this final week of August, you may not have been thrilled with what you saw – and it turns out your senses were right.

As often happens in August, Lake Ontario was a thick brown and green from the shoreline to about 15 feet out, before it starts to clear up.

Thursday morning, workers along the beach confirmed it would be closed to swimming, citing clarity issues. The cloudy water impedes lifeguards’ ability to see swimmers beneath the water. The beach was closed for the same reason Sunday and access limited on Monday.

But what about water quality ? News 8 reached out to Monroe County.

The county directed us to test results on New York’s Coastal Beach Quality Website which indicated results were well within acceptable limits early in the week. The county said numbers above 235 MPN (most probable number) would exceed quality water standards. Samples from the beginning of the week peaked at 166 MPN, well within the safe zone.

A check of the state site Thursday morning told a different story, with E. Coli indicators at 1827 MPN on Ontario Beach East, and 4902 MPN on Ontario Beach West.

According to county officials, while not always 100% accurate, predictive modeling for Wednesday found “an exceedance of bacteriological standards,” and led to a closure of the beach Thursday “because of the model prediction, before sample results were available.”

The county explained it clears out as much accumulated algae each morning. At Ontario Beach, that algae is typically Cladophora, which is safe initially, but can result in bacteriological growth as it decays.

Full response from Monroe County:

The values are accurate.  Water quality bacteriological standards were exceeded at Ontario Beach on 8/28/2024.

For background, Monroe County does far more sampling, observations, and modeling than what is required due to constant changes in water conditions.  Samples are collected daily at two sections of the Ontario Beach swimming area.  Analysis of these samples takes approximately 18 hours, so sample results for any given day are not available until the following day. To better protect public health, predictive modeling is used to preemptively close the beach when an exceedance of water quality standards is predicted.  When the predictive model indicates water quality standards will be exceeded, the beach is closed and the reasoning is posted on the NYS Coastal Beach website as well as communicated to beach operators.  Because we rely heavily on modeling, closure reasons posted are usually the main contributing model criteria that leads to the prediction of an exceedance and closure (i.e. Poor water clarity, or rainfall).

Predictive modeling is not 100% accurate, however on 8/28/2024 modelling did accurately predict an exceedance of bacteriological standards.  Ontario Beach was closed on this day because of the model prediction, before sample results were available.  The main contributing model criteria leading to the preemptive closure in this case was poor water clarity as measured with a secchi disk.

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