The federal government has approved new rules on mercury in California waterways.
Environmentalists like Alex Keeble-Toll with The Sierra Fund in Nevada City are applauding the decision.
"It's increased recognition that there is an imminent public health threat associated with mercury in fish," says Keeble-Toll. "If we can create water quality objectives that are more stringent so that people do have to address sources of mercury in order to meet their water quality objectives, then it means that there'll be less mercury in the fish."
"In our region there's long been a perception that in the Sierra Nevada, because it's so beautiful, the fish must be safe to eat," says Keeble-Toll.
But much of the fish isn't. Gold Rush-era mining operations released millions of pounds of naturally occurring mercury into state waterways.
San Francisco Baykeeper's Erica Maharg says with the new federally approved water quality criteria, regional water boards throughout the state will have to identify which waterways people are using to catch fish.
"And then once that use is recognized, they will have to make plans to ensure that the fish people eat is safe."
Including plans for reducing pollution and setting goals to make sure those reductions are met.
"We have many Californians around the bay who are not tribal members but feed their families from the bay waters and we need to make sure that those families are protected when they do that," says Maharg.
The EPA says the new rules set mercury limits in fish tissue.