Support WBURMarijuana Farms Take Root In National ParksPlay07:23Download AudioMartin KasteMay 12, 2009 ShareSteve Yu, a special agent with the National Park Service, looks for evidence of marijuana farms in the backcountry of Yosemite.
Steve Yu, a special agent with the National Park Service, looks for evidence of marijuana farms in the backcountry of Yosemite.