FREELAND — Scientists from the United States Geological Survey began testing for mercury levels in Holmes Harbor Monday.

Not to worry: The study is being done to compare levels of toxic mercury with data found in Sinclair Inlet near the Navy base in Bremerton.

“We chose this location as a reference site,” said research scientist David Krabbenhoft.

“The Navy is concerned over possible high levels of mercury near their facilities, but we need to be able to quantify the difference,” he said.

Other spots being checked besides Whidbey Island include Budd Inlet near Olympia and Liberty Bay off Poulsbo.

Krabbenhoft said there should be only trace levels of mercury found in the waters of Holmes Harbor, which is naturally accruing from the atmosphere.

“The Navy is funding the study, and if it shows that there are significant mercury levels in Sinclair Inlet, they’re on the hook for it,” he said. “Our job is to do relevant research in the public interest and that’s why we’re here.”

Samples taken will be analyzed and the results forwarded to the Navy by the end of September.

Mercury poisoning is a disease caused by exposure to mercury or its toxic compounds. Mercury is a cumulative heavy metal poison that with sufficient exposure can damage the central nervous system and other organs, or organ systems such as the liver or gastrointestinal tract.

Krabbenhoft is from Wisconsin — this is his first trip to Whidbey. Pointing to a bald eagle circling high above, he said mercury poisoning is a serious disease.

“Trying to protect something that beautiful is a worthwhile goal,” he said.

For information, visit www.infotrek.er.usgs.gov/mercury.