Intersex Fish Found in Potomac River

Sept. 6, 2006 — -- Intersex fish have been found in the Potomac River in Washington, D.C., where scientists have discovered immature eggs in the sex organs of male smallmouth and largemouth bass.

"It indicates a problem we need to be concerned about," says Vicki Blazer, the fish pathologist at the U.S. Geological Survey, who has studied the problem since 2003, after a large fish kill in the south branch of the Potomac. Blazer first noticed the intersex abnormality in 2004. "We need to try to figure out what's going on."

But so far, scientists have not been unable to pinpoint exactly what contaminants have caused this abnormality. And since the health of a fish indicates the health of the water, environmentalists have asked if the contaminants affecting the fish pose any danger to the millions of people whose tap water comes from the Potomac.

"We know pollution is in the water," says Ed Merrifield, executive director of the Potomac Riverkeeper, an environmental group. "All water runs downhill. If they can't tell us what the problem is, how can they tell us it's not in our water? There may be a danger."

So far, Washington's water utilities say they've found no evidence that tap water taken from the Potomac is unsafe. "There is no indication we have any public health concerns with our finished water," says Charles Murray, the general manger of the Fairfax County Water Authority, which depends on the Potomac River as the water source for half of its 1.4 million northern Virginia customers.

Murray is confident that the barriers and water treatment systems in place can remove a broad range of compounds. "We'd like to know more, but at this point are we concerned that what we have in place is not protecting the public health? No."

The first intersex fish in the area were found three years ago in a West Virginia stream, 200 miles upstream from Washington. After that unusual discovery, scientists set up testing sites all around the region.