The San Francisco Estuary Institute says largemouth bass taken from lower Crystal Springs Reservoir in San Mateo County had some of the highest mercury levels in the state.
However, the contamination doesn't indicate that the water itself is unsafe.
Researchers sampled sport fish at nearly 300 California lakes for mercury and other contaminants. The results found 21 percent of the lakes had at least one fish species with a mercury level considered unsafe to eat by children.
