A news segment featuring a local activist group’s investigation into mercury levels in restaurant seafood earned the Los Angeles-based station NBC 4-KTTV an Emmy for medical news coverage this week. In an undercover investigation, San Geronimo Valley-based Got Mercury took samples from a variety of California sushi bars and other eateries. Independent testing revealed harmful mercury levels—sometimes twice the legal amount—in tuna and swordfish. “This is an important message to publicize because it’s such a…