The federal report, posted Thursday on the website of the Environmental Protection Agency's Chesapeake Bay program, found nearly 75 percent of the bay's tidal waters are contaminated by toxic chemicals, The Baltimore Sun reported.
The chemicals, which include mercury, polychlorinated biphenyls, or PCBs, are tainting fish.
"Since 2000, new concerns, such as intersex conditions in fish, have arisen," the report says. "Although the causes are undetermined, there is increasing evidence that contaminant exposures may play a role."
In reaction to the report, advocates are making a push for Maryland lawmakers to increase data collection and research into the use and potential effects of pesticides and other chemicals that have been found in the bay.
"Science is telling us in some cases there is no safe level of exposure," Rebecca Ruggles, coordinator of the Maryland Environmental Health Network, said during a briefing Thursday in Annapolis, the state capital.