Aug. 5, 2002 – In a long-term study that looked at water contaminants in marinas and areas adjacent to marinas on St. Thomas and St. John, researchers found the two types of places had similar pollution problems.
"There wasn't really a significant difference between water quality inside and outside marinas," said Lynne Hinkey, who now works with the Seagrant program at the National Oceanic and Atmospheric Administration in Charleston, South Carolina.
However, when marinas and adjacent areas were compared to undeveloped areas, the study found significant differences in water contamination.
Hinkey, who formerly worked with the Seagrant program at the University of the Virgin Islands, and University of Rhode Island graduate student Barry Volson, who got his undergraduate degree from UVI, conducted the study. It was undertaken for the Association of Marina Operators of the Virgin Islands and the University of Puerto Rico Department of Marine Sciences.
The researchers looked at Crown Bay Marina, Independent Boat Yard and American Yacht Harbor on St. Thomas, and at Cruz Bay on St. John. Hinkey said that because Cruz Bay has a large concentration of boats, it was expected to have characteristics similar to those of a marina.
As a control, the study used Great Bay on St. Thomas's East End. Since the study was done before the Ritz Carlton began its recent condominium construction project, the area was still in an undeveloped state. ("Thank God I finished it before the Ritz condos," Hinkey said.)
A subsequent study by Hinkey and Volson measured contaminants often found at marinas. For this study, they picked the two marinas at opposite ends of the spectrum — Crown Bay as St. Thomas's newest marina, which is breezy and has good flushing, and Independent Boat Yard as the island's oldest marina, tucked back in the mangroves.
The scientists looked for petroleum from engines and heavy metals from bottom paint, maintenance, batteries and keels. They also looked at water contaminants from non-marina sources — for example, PCB's from industrial operations such as the Water and Power Authority and pesticides from government and private mosquito-control programs.
Most of the pollutants found were site specific. Petroleum products were found near fuel docks, metals were near areas associated with runoff from maintenance sites, and both petroleum products and metals were found near storm water drainage areas. Many of the contaminants found at marinas are the result of "past usage and practices," not current marina or boating practices, the researchers noted.
Both studies found that site and design are big factors in determining water and sediment quality impacts on marinas. "Those marinas are sited perfectly for what they have," Hinkey said.
She said the clay bottom at Independent Boat Yard binds up the heavy metals found in bottom paint. And at Crown Bay Marina, petroleum from the nearby WAPA plant gets washed out of the sandy soil.
"But there was no plan on the part of either marina," Hinkey said, referring to coincidences that put the marinas at locations right for their conditions.
She also said that boaters get a bad rap for polluting marinas and harbors with the contents of their sewage tanks. "The coliform counts were surprisingly low," she said. In fact, she said, the worst sewage pollution problem is caused by the contents of malfunctioning septic tanks washing down the hillsides into the water below.
The study suggests targeting management practices toward specific sources of pollution. This means marina owners must find out what causes the pollution at their particular locales and determine effective actions to stop it.
For example, Hinkey noted, putting oil containment booms at fuel docks doesn't protect marina waters from petroleum that comes from parking lots and roadways; vegetation planted between the marina and the water is the best general way to reduce pollution of that type.
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