The Potomac River, which flows through Washington, DC, has nurtured trade, cultures, migration, and living resources for more than 10,000 years.
Captain John Smith visited the Potomac in 1608. He found fish “lying so thicke with their heads above water, (that) for want of nets, we attempted to catch them with a frying pan.”
It’s a different story today. Some species of male fish in the Potomac River are developing female sexual traits at a frequency higher than scientists have seen before, raising concerns about pollutants in a waterway that provides drinking water for millions of people.
AP reports the so-called “intersex fish,” which produce immature eggs in their testes, were discovered in the Potomac rivershed in 2003 and have also been found in other parts of the country.
But the frequency that the U.S. Geological Surveys found last year is much higher than what has been found elsewhere, said fish pathologist Vicki Blazer.
In some Potomac tributaries, nearly all of the male smallmouth bass caught in last year’s survey were the abnormal fish. In the Potomac itself, seven of 13 largemouth bass exhibited female characteristics, including three that were producing eggs.
Female fish caught in the survey did not develop any unusual sex traits, though fish of both sexes exhibited lesions and other pollution-related problems, said Blazer, who coordinated the survey.
Certain chemicals and pesticides are believed to stimulate estrogen production. Also, estrogen from birth control pills and human waste can make its way from sewage treatment plants to the waterways.