The Harvard Board of Health issued a no-swimming order for the town beach on Aug. 24 because of a rapid overgrowth of algae over the weekend—called an ‘algal bloom’—in Bare Hill Pond. At its Aug. 25 meeting, the board said it issued the order because underwater visibility was too poor for safe swimming. The board also voted to have the water tested for cyanobacteria, a type of blue-green algae that is sometimes responsible for an algal bloom. This type of algae can produce cyanotoxins that are poisonous to humans, fish, wildlife, and pets.
A sign at the town beach Tuesday, Aug. 25, gives swimmers the bad news. (Courtesy photo)
Beach staff and residents who live by the pond noticed it was turning an eerie shade of green over the weekend. Bruce Leicher, chair of the Bare Hill Pond Watershed Management Committee, notified the committee’s wetlands consultant, Wendy Gendron, who confirmed it was an algal bloom. She recommended the water be tested to determine if it was toxic. Leicher reported Gendron’s recommendation to the Board of Health. Leicher posted on Nextdoor that there have been one or two algal blooms in the past 15 years. The blooms were not toxic and cleared in five to seven days.
When the board discussed testing, Nashoba Associated Boards of Health Agent Ira Grossman, who issued the order, told the board he did so because of poor visual clarity in the water, not because it might be toxic. “I’m not recommending we test,” he said. “It’s late in the season.” Grossman also pointed out that the beach is not officially open and is already posted with “Swim at your own risk” signs.
But Board of Health Chair Sharon McCarthy said the Department of Public Health (DPH) offered to test the water at the beach for free—once now, and once after the algae clears. The board voted unanimously to accept DPH’s offer for free testing. The Press asked if the no-swimming order would be lifted when the algae clears even if test results are not yet back, and member Chris Mitchell said the board would consider it. Grossman confirmed that the pond is still open for boating and fishing.
Algal bloom could put people and animals at risk
According to the Centers for Disease Control and Prevention (CDC), if the algal bloom is contaminating the water with cyanotoxins, people and animals could get sick from swimming, kayaking, fishing, or wading through the water, breathing in tiny water droplets or mist, drinking the water, or eating fish caught in the water. CDC lists the following symptoms: skin, eye, nose, or throat irritation, abdominal pain, headache, neurological symptoms, vomiting, and diarrhea.
The CDC also warns that animals are especially vulnerable and can die within hours of exposure. It advises contacting a veterinarian without delay if a sick pet is suspected of having been in contact with a harmful algal bloom. Symptoms in animals include excessive salivation, weakness, staggered walking, difficulty breathing, and convulsions.
The board told the Press it would post more specific information at the pond (including warnings about pets) if the water tests positive for cyanobacteria. It did not know when test results will be available.
