12:40 pm, Thursday
The Chilmark board of health this morning officially closed Squibnocket Beach to swimming but unofficially told visitors seeking an escape from the blistering heat, “Swim at your own risk.”
Board of health members do not think there is much risk, Marina Lent, board administrator/inspector, said. If the board did, she said, they would not have authorized her to post an informal town sign that provides details on the reasons for the closing, next to the formal notice prohibiting swimming.
The most recent water test for enterococci bacteria, an indicator organism for more dangerous bacteria, taken on Monday, July 18, was well under the state limit of 104 colony forming units per 100 milliliters of water (cfu/100 mil).
However, the average bacteria count did not meet the state standard called “geometric mean trend.” The major factor was an exceedingly high result received on July 5 of 2,420 cfu/100 mil, the limit of the measurement chart.
While the single day standard provides a “snapshot” of water quality, the geometric mean measurement is based on the most recent five test results, and computes trends in water quality over time.
Until today, the board of health was only testing on a weekly basis. Ms. Lent said she was not aware of the need to fall under the geometric mean until she received a call from the DPH.
In an email to The Times Thursday morning, Ms. Lent said DPH official Irena Draksic telephoned the Chilmark board of health this morning and said the town is required to post a closure for Squibnocket Beach, because the average bacterial count is still higher than is allowed.
Ms. Lent said, had she known of that requirement she would have begun testing daily after July 5 in order to move the 2,420 result out of the equation. Oak Bluffs encountered a similar situation, closing, reopening and then closing beaches.
Chilmark has the results of tests conducted on July 5 (2,420), July 7 (49), July 11 (114) and July 18 (fewer than 10).
She said she tested this morning and if that result, not available until Friday, is below 74, the DPH has cleared the town to reopen the beach, she said.
Ms. Lent said she has informed DPH of the town’s decision under the current circumstances to post a “Swim at your own risk” notice. She said that if there are mixed results the town would not allow swimming, but in this case the board of health made the determination that the July 5 test is not representative of water quality.
She said it is a judgment call the town is comfortable making. Asked about DPH, she said, “They understand the situation.”
Squibnocket is a private town beach that fronts on the Atlantic Ocean. There are limited parking, lifeguards and commanding views of the South Shore and Squibnocket Point to the southwest.
Ms. Lent said she has posted the required closure notice and next to that a town sign.
It reads: “This beach closure sign is posted per Mass Department of Health regulations.
“These regulations require that the average of the last five bacterial water samples must be below a certain level. Our average is still slightly above the required limit.
“On July 5, 2011, we experienced an anomalous reading of 2,420. All tests since that date have been at or below safe limits, with the exception of a test on 7/11 which was 10 points above the limit of 104 set by the Department of Public Health.
“Our last test, on July 18, 2011, measured 27, well below the safe level of 104.
“You may choose to swim at your own risk.”