Possible toxic blue-green algae bloom found in Hemlock Lake, drinking water unaffected
A possible blue-green algae bloom in Hemlock Lake, the primary source of Rochester drinking water, was identified Thursday afternoon.
Blue-green algae can release toxins that are harmful to human and animal health, and discovery of a bloom in a drinking-water source is always a matter of some concern.
City spokesman Justin Roj said the possible bloom has had no effect on the drinking water supply and was already beginning to break up by Friday. By Monday, no additional reports had been made.
The bloom at Hemlock was found in the lake’s open water. No other information about the occurrence was available. The event was posted late Friday on New York state’s harmful algal bloom alert page.
The bloom came as other Finger Lakes, including Honeoye and Cayuga, are wrestling with multiple reported blooms.
Algal blooms, once almost unheard of in pristine Hemlock and its smaller sister lake, Canadice, have now occurred in each of the last three years.
Two summers ago, small blooms were detected on both lakes, giving rise to expanded surveillance by city water-bureau workers. Neither posed any threat to drinking-water quality.
In July of last year, the city detected another algal bloom in Hemlock about 1,000 feet from the intake for its water filtration plant. That bloom, which was not publicized at the time, may have released a small amount of toxin but also posed no threat, city officials told the Democrat and Chronicle recently.
In recent years, Owasco and Skaneateles lakes experienced serious blooms that did present problems for drinking water customers.
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