Story highlights Group wants to see grizzly bears reintroduced in California mountains

But state officials worried about possible problems with human, livestock interactions

San Francisco (CNN) The grizzly bear is a well-known California symbol. After all, it's on the state flag. But the only place you'll find them in California is at the San Francisco Zoo. A conservation group believes they should be brought back into the wild, ideally in the iconic Sierra Nevada mountain range.

"We think it's possible to bring the grizzly back," said Jeff Miller with the Center for Biological Diversity.

The organization has launched an online petition drive urging state and wildlife officials to consider the feasibility of bringing back the grizzly, which can get up to nearly a 1,000 pounds. About 20,000 people have signed it.

It's not clear how many bears would constitute a viable population. Proponents say large predators are important to keeping ecosystems in good shape.

"I think the state owes it to the people of California to take a good hard look," said Miller, who believes that humans would have little to fear because "we're not a preferred food source."

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