In October, levels of faecal bacteria in the waters surrounding the east end of Grand Cayman were found to be nearly 50 times greater than accepted safety standards.
The information on the sample tests was made available following a Freedom of Information request.
Although there are beaches and dive sites throughout the areas sampled, no public notification of the extreme levels of enterococci bacteria was issued. No subsequent testing of the water has been conducted.
The Department of Environmental Health is responsible for sampling the waters of designated public beaches around the island each quarter. But that testing often does not get done. The same is true of follow-up testing when bacteria levels are high or suspected of being high.
Enterococci is measured in the number of observed colony forming units per 100 millilitres of water. The US Environmental Protection Agency has established a safe limit of 35 units of enterococci per 100 mL. Florida issues a public advisory when levels exceed 70 units. Beaches in Massachusetts are closed when levels exceed 100 units for a single water sample. In California, the level is 104 units.
On Oct. 31, 2018, samples from Bodden Town Public Beach were measured at 1,733 units. Two other beaches, East End Heritage Beach and North Side Public Beach had readings of 1,533 units and 1,300 units respectively.
Laboratory manager Antoinette Johnson said the department does not have an established policy on issuing public warnings or closing beaches. Before taking such action in response to elevated bacteria levels, subsequent tests would be done.
“It would take more than one sample,” she said, before the department would issue an alert or move to close a beach area. “The fact that a second sample wasn’t done could have been (that) the conditions weren’t right for us to do one right away.”
She said conditions such as rough seas or recent rainfall, resulting in runoff or overflow from septic tanks near beaches, can hamper gathering acceptable samples and also elevate levels of the bacteria. Conditions at the three test sites were listed as either choppy or rough. Those same conditions, she said, may have kept the department from getting any follow-up readings.
The Department of Environmental Health keeps track of any reports from local hospitals regarding illness that might be connected to environmental factors, Johnson said. “Nothing of the sort” was reported in the time period surrounding October’s tests, she said.
The department lacks adequate personnel to make sure testing of Cayman’s beach waters takes place on a regular basis, she said. When samples are taken, old lab equipment sometimes keeps lab personnel from getting accurate readings.
The lab, she said, is not meeting the recommendations established by the World Health Organization for frequency of testing.
Johnson said the elevated levels recorded in October were likely due to an influx of sargassum and its subsequent decay. A large influx of the seaweed had been reported three weeks prior to the testing. Sargassum harbours many small marine animals and the decay of those animals can result in elevated enterococci bacteria levels.
The tests from the three sites were the only quantifiable results falling outside accepted limits in the past two years of testing. However, there were two occasions – in March 2018 and May 2017 – when the laboratory reported the units in the samples were too numerous to count. On the first occasion, it was deemed the samples were viable and that the levels were ‘unsatisfactory’.
Sets of tests taken in May 2017 and February and April 2018 show readings well below the accepted 35-unit threshold. With the exception on one reading of 10 units at Eden Rock, all results were zero or in the single digits.
Johnson said that if and when a spike cannot be related to external conditions, the department would take action.
“Every rainfall event will affect our results,” Johnson said. “If we see a spike at a particular beach and we can’t relate it to rough seas or recent rainfall, [additional testing would follow]. Any changes that are persistent, we would insist on a sanitary investigation.”
That could include inspection of nearby septic tanks or other waste facilities that might contaminate the water.
Johnson said residents and visitors should have confidence in the safety of local waters. In her years in the lab, she said, she could not recall an instance of an illness being tied to recreational swimming off the beaches.
“We’ve had one or two mild infections with pools,” she said, as well as some tied to groundwater. “But nothing with recreational use.”