Friday, West Tisbury health officials allowed the reopening of four public beaches, after test results revealed that worrisome high levels of enterococci bacteria had declined to levels below the state standard for safe swimming.
Results from tests taken Tuesday, july 5 led the town to close the four heavily used beaches — Lambert’s Cove Beach on Vineyard Sound, Uncle Seth’s Pond off Lambert’s Cove Road, Long Cove Pond, and Tisbury Great Pond beach, part of The Trustees of Reservations Long Point property on the Island’s south shore — to swimming on Thursday.
John Powers, the West Tisbury health agent, told The Times Friday that a conclusive judgment as to what caused the unacceptable levels earlier in the week remains elusive.
At Lambert’s Cove Beach the level of bacteria was 15 times above the acceptable level.
According to the Massachusetts Department of Environmental Protection (DEP), enterococci bacteria are an indicator organism that may mean water is contaminated by fecal coliform bacteria.
High levels of enterococcus can cause skin irritation, vomiting, or diarrhea.
The Bureau of Environmental Health (BEH) posts beach water quality information on the Massachusetts Public Health Department website.
Water samples taken on July 5, showed enterococci counts of 1,553 colony forming units per 100 milliliters (cfu/ml) at the north end of Lambert’s Cove Beach and 548 cfu/100 ml at the south end, according to the department website. In marine waters, the accepted level of enterococci for a single sample is 104 colony forming units per 100 milliliters.
A sample taken the same day at the Tisbury Great Pond Long Point sampling site showed a count of 2,420 cfu/100 ml. Long Cove Pond was also 2,420.
“I’ve never seen it that high before,” Mr. Powers told The Times.
Uncle Seth’s Pond had a count of 73. The accepted level for freshwater is 61.
Enterococci are a group of bacterial species within the streptococcus genus, some of which (e.g. streptococcus faecalis) are typically found in human and animal intestines and are therefore present in sewage. These tests are also referred to as indicator organisms.
Any sample with a count greater than 104 cfu/100 ml is called an “exceedance”, which requires that the beach be posted.
The BEH advises that swimming in polluted water can cause gastrointestinal symptoms such as nausea, vomiting, diarrhea, and abdominal pain, respiratory symptoms such as sore throat, cough, runny nose, and sneezing, eye and ear symptoms including irritation, earache, and itchiness, dermatological symptoms like skin rash and itching, and flu-like symptoms such as fever and chills.
Most of these symptoms are minor most of the time but can occasionally be more serious, especially in sensitive populations (e.g. immuno-compromised children and elderly).
Last summer, beach closings occurred in Oak Bluffs, Edgartown and West Tisbury during some of the busiest weeks of the summer season.
Beach closings have been a regular occurrence along the Massachusetts coast in recent summers.