Martha's Vineyard beach water testing proves accurate
Photo by Steve Myrick
State officials, local health agents, and officials at the Wampanoag Environmental Testing Lab say recent controlled testing of split samples by three different labs show all the labs are accurate, within accepted statistical probabilities, when they test local beach water for harmful bacteria.
But the second summer of beach closings on Martha's Vineyard at the height of the summer tourist season continues to confound local officials, residents, and tourists. State and lab officials say, however, that the extremely high levels of bacteria measured recently on the Island are not out of the ordinary for similar beaches in other parts of Massachusetts.
The Wampanoag testing lab contracts with the state Department of Public Health to test water from Island beaches. Lab officials are confident the tests on bottled samples of beach water delivered to the lab by local health agents accurately reflect the bacteria levels in those samples.
"I understand that people are unhappy with the results, but I can guarantee what's in the bottle is what you've got," said Brett Stearns, Wampanoag Natural Resources Director.
In order to test whether high levels of bacteria might be the result of some deficiency in testing the water samples, the state Bureau of Environmental Health organized a controlled test last week for health officials in Edgartown and Oak Bluffs.
On July 18, samples from Island beaches were gathered as usual, and each one carefully split into separate samples. Edgartown health agent Matt Poole sent samples to three labs, the Wampanoag lab in Aquinnah, a testing lab operated by the town of Tisbury, and a testing lab operated by the town of Chatham.
Oak Bluffs health agent Shirley Fauteaux sent samples to the Wampanoag Lab and the Chatham lab. The local health agents, along with state officials, wanted to see if different labs testing the same water arrived at the same results.
The labs tested independently for enterococci bacteria. Enterococci is an indicator organism that signals the presence of other bacteria, both harmful and benign. It is the accepted standard for the most accurate measurement of harmful bacteria.
In some of the samples, there was variation in the level of enterococci measured by the three labs. State environmental officials, local health agents, and lab officials agreed, however, that variation in all samples fell within the statistical range of accuracy, showing that each lab came up independently with the same result. They said some variation in individual tests is to be expected.
The statistical accuracy is not guesswork. The variation is rated according to a widely accepted standard for the tests used by each lab, Kendra Newick, Wampanoag lab manager, said.
Tests by the Wampanoag lab of water taken from Edgartown's South Beach at the right fork on July 18, showed 110 colony forming units of enterococci per 100 milliliters (cfu/100ml). Tests of the same sample from the Tisbury lab showed 52 cfu/100ml.
While those results are within the statistical range of accuracy, the Wampanoag lab results are slightly above the state's single sample standard of 104 cfu/100ml. Under state regulations, the Wampanoag lab results would have required the closing of South Beach for the first time recent memory. Health agent Matt Poole said state officials accepted the Tisbury lab results, and did not require the beach to be closed.
In another split sample, taken from South Beach at the left fork, the Wampanoag lab measured 10 cfu/100ml, while the Tisbury lab measured 41 cfu/100ml. The two South Beach sample points are less than a mile apart. Those results also fall within the statistical range of accuracy. Both results are below the single sample standard, and would not have required closing the beach. Samples tested by the Chatham lab from both sampling points also showed results within the accuracy range.
Similarly, the Wampanoag Lab showed a count of 130 cfu/100ml for Pay Beach in Oak Bluffs, above the state standard for a single sample test. The Chatham lab showed 91 cfu/100 ml, within the range of statistical accuracy. The state accepted the Chatham result and did not require a beach closure.
Mr. Poole said the split sample tests show that all three labs are returning accurate results. He disputed the notion that he was critical of the Wampanoag lab.
"I'm not pointing any fingers at anyone," he said.
Mr. Poole was concerned about tests on a control sample, or "trip blank," sent to the Wampanoag Lab. That sample, taken from a bottle of Poland Springs water bought at an Edgartown convenience store, showed 20 cfu/100ml. The Tisbury lab showed less than 10 cfu/100ml. Mr. Poole said he would expect a sample of bottled water or tap water to contain no enterococci bacteria.
He said he is also frustrated with the time consuming process of sampling and testing beach water, which he believes is a relatively low threat to public health.
"I think we've lost perspective," Mr. Poole said. "It's so disruptive to everything else we're charged with doing. There are more urgent things that need attention."
Testing the testers
Kendra Newick, lab manager for the Wampanoag lab, said she uses thorough and redundant measures at every step in the testing process to make sure the lab returns accurate results.
Her control measures include daily calibration of instruments, blind control tests of every batch of water samples delivered, and three tests to ensure sample bottles are sterile.
She also has external controls. Periodically, she orders samples of water from a certified commercial lab that contain levels of enterococci unknown to her. She measures the bacteria and sends the results back to the lab that supplied the samples, to make sure she is measuring accurately.
The lab is also subject to frequent federal and state certifications, as well regular audits of its records to ensure the lab uses the correct testing protocols. On Tuesday, state officials conducted an annual audit of the lab records and paperwork, scheduled before the recent beach closings. Also Tuesday, officials from the federal Environmental Protection Agency came to check the lab's work.
Unlike other testing, the Wampanoag lab does not control the gathering of samples for beach water quality. Local health agents are responsible for gathering and transporting samples to the lab.
Health agents gathered water samples according to precise state guidelines that cover the depth, distance from shore, ocean current, and sterile equipment. The guidelines also control the time and temperature of the samples as the bottles are transported to a lab.
Mr. Stearns is confident the local officials are working according to state guidelines.
"They've all been trained, they all know what they're doing," Mr. Stearns said.
How can it be?
On an Island where beaches are the anchor of tourism, and where tourism drives much of the local economy, closing beaches is a hyper-sensitive subject. To many, it seems inconceivable that a beach like Long Point on the south side of the Island, open to the sea and surrounded by hundreds of acres of undeveloped land, could have bacteria levels higher than urban beaches in Boston, higher than beaches on Cape Cod, and higher than other Island beaches just a few hundred yards away.
"We've got open Atlantic ocean, with no potential source you could investigate as the origin of this contamination, producing crazy results," Mr. Poole said.
While the source of the contamination is unknown, scientists and administrators charged with monitoring water quality say the high bacteria counts are not unusual, and most likely explained by environmental factors.
The most likely factor, they say, is rainfall.
"One of the things we've noticed, and it seems to have gotten lost," Suzanne Condon, director of the state's Bureau of Environmental Health, "is that when the first set of very high results came back, the beach samples were actually collected on Monday following a heavy rain the Saturday before. Heavy rain almost universally will cause beach closures."
Rainfall washes animal waste and other pollution into the water and onto the beaches. The bacteria can live and breed in sand.
Ms. Condon refers to beach water samples collected by local health agents on July 11, which triggered closure of popular beaches in Oak Bluffs, West Tisbury, Chilmark.
The Island experienced heavy rain on the preceding Friday evening into Saturday morning. While National Weather Service precipitation data for that period on Martha's Vineyard is incomplete, records for Hyannis and Chatham show heavy rainfall. In Hyannis, records show 2.27 inches of rain fell. In Chatham, records show 2.76 inches of rain.
"It's really not out of the ordinary for the conditions we've seen, especially the rainfall," Mr. Stearns said. "I predicted when we had that rain we were going to have closures."
"We have seen this across the state," Ms. Condon said.
Another possible cause of harmful bacteria is vegetation on the beach, which often washes up after a heavy storm churns the ocean water. Course brown seaweed, called wrack, can collect bacteria.
"I drove by the beach on the Monday morning those samples were collected," Mr. Poole said. "The beach was covered with seaweed."