The study released by the state's Water Board found elevated levels of toxic chemicals, specifically methylmercury and PCBs, in fish caught in San Diego Bay.
The six-year, $4.5 million study tested 42 spots along California's coastal waters and found three-quarters of them had at least moderate levels of toxins which have been linked to potential health effects, from learning disabilities to cancer.
Despite the findings, the state hasn't issued an official health warning. Officials say more research needs to be done.
The study was the largest of its kind ever conducted statewide.